Kele KNET-CO2 BACnet and Modbus Networked CO2 Sensor/Transmitter User Manual

User Manual for Kele models including: KNET-CO2 BACnet and Modbus Networked CO2 Sensor Transmitter, KNET-CO2, BACnet and Modbus Networked CO2 Sensor Transmitter, Modbus Networked CO2 Sensor Transmitter, Networked CO2 Sensor Transmitter, CO2 Sensor Transmitter, Sensor Transmitter, Transmitter

M380-CO2 manual

Mike Muller;RAJ

kele.com | Kele 34-08-2000 | Gas & Specialty Sensors | Carbon Dioxide

File Info : application/pdf, 24 Pages, 955.17KB

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KNET-CO2
BACnet and Modbus Networked CO2 Sensor/Transmitter with Relay Preliminary
User's Manual

Last Rev Date: 12/16/24

3300 Brother Boulevard Memphis, TN 38133
Phone: 877-826-9045 www.kele.com

90-0018-0a

KNET-CO2 User's Manual

Table of Contents
Feature Overview.......................................................................................................................................... 3 CO2 Sensor ............................................................................................................................................... 3 Relay......................................................................................................................................................... 3 BACnet ..................................................................................................................................................... 3 Modbus ..................................................................................................................................................... 3 Network Topology.................................................................................................................................... 4 NEARcom ................................................................................................................................................ 5 Calibration ................................................................................................................................................ 5
Specifications ................................................................................................................................................ 6 Installation..................................................................................................................................................... 7
Mechanical ............................................................................................................................................... 7 Wiring....................................................................................................................................................... 7
Power.................................................................................................................................................... 7
Relay .................................................................................................................................................... 8
Network Connection ............................................................................................................................ 8
Configuration ................................................................................................................................................ 9 NEARcom ................................................................................................................................................ 9 Inspecting the KNET-CO2 Settings ..................................................................................................... 9
Configuration Procedure ........................................................................................................................ 12 Example configuration BACnet ...................................................................................................... 12
Example configuration Modbus ...................................................................................................... 13 Operation .................................................................................................................................................... 14
Relay....................................................................................................................................................... 14 CO2 Sensor ............................................................................................................................................. 14
Sensor Supervision ............................................................................................................................. 14
BACnet ................................................................................................................................................... 14 Modbus ................................................................................................................................................... 15 Calibration................................................................................................................................................... 16 Calibration Procedure ............................................................................................................................. 16 Disclaimers ................................................................................................................................................. 17 Life Safety .............................................................................................................................................. 17 Warranty ..................................................................................................................................................... 17 Appendix 1: BACnet objects and default values ........................................................................................ 18 Device Object ......................................................................................................................................... 18 CO2 - Analog Input Object 1 ................................................................................................................. 19 Relay Binary Output Object 1 ............................................................................................................. 20 Relay Setpoint - Analog Value Object 1 ................................................................................................ 21 Enable Local Relay Control - Binary Value Object 1 ............................................................................ 21 Appendix 2: Modbus registers ................................................................................................................... 22 Appendix 3: 3rd Party Software Components & Licenses ........................................................................ 23

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Page 2

KNET-CO2 User's Manual
Feature Overview
The KNET-CO2 is a supervised, network-capable CO2 sensor/transmitter with a single relay. It can be configured for local concentration based or network-controlled actuation. The KNET-CO2 can communicate using BACnet MS/TP, Modbus RTU, or Modbus ASCII, all using an RS-485 transport layer. The KNET-CO2 has a supervised, dual-beam CO2 sensor for long-term stability without the need for frequent re-calibration. Configuration of settings is accomplished using the NEARcom app with an NFC-capable smartphone for easy `fill in the blanks' network setup.
CO2 Sensor
The KNET-CO2 uses a self-compensating `dual beam', NDIR (Non-Dispersive InfraRed) CO2 detection system with a second IR detector to measure and eliminate the major inherent drift mechanisms (source amplitude degradation and sensor-wall reflectivity changes) for greatly enhanced long-term accuracy. To achieve comparable performance, single beam systems need `self-calibration' algorithms that can be wildly inaccurate in changing building occupancy profiles. The KNET-CO2 can be used in any building occupancy profile with no compromise in long-term accuracy.
The gas detection system is internally supervised, so the KNET-CO2 will immediately notify its controller in the unlikely event of failure.
Relay
The KNET-CO2 has a dry-contact, 2-Amp rated, Single-Pole Double-Throw (Form C) pilot relay that can be controlled by two different mechanisms; local setpoint or network control. With Setpoint Control, the relay is controlled locally by the device based on its current CO2 setpoint. Network Control passes control of the relay to the active network interface where it is modeled either as a binary output (BACnet) or a holding register (Modbus).
BACnet
BACnet (Building Automation and Control network) is a standardized communication protocol used for building automation created by ASHRAE (American Society of Heating, Refrigeration, and Air-Conditioning Engineers). BACnet specifies a vendor-independent set of models and messages that enable equipment from multiple manufacturers to be integrated within the same control network. BACnet can use several different physical communication systems depending on the constraints of the system, the most common being BACnet/MSTP and BACnet/IP. Most end devices only support one transport layer; bridges are available that can translate messages between different transport layers.
The KNET-CO2 supports only BACnet/MSTP using RS-485.
Modbus
Modbus is an industrial control protocol. It has somewhat less overhead than BACnet, allowing fewer data types and providing less context information about modeled objects. In Modbus all data is held in registers that can be read or written to interact with the values they model (e.g., CO2 reading, relay state, etc.). A single client device sends requests to servers such as the KNET-CO2. Servers will not initiate communication unless they are directly addressed.
Modbus supports several modes of communication; RTU, ASCII, and TCP all using the same data model. Modbus RTU (remote terminal unit) and Modbus ASCII both use asynchronous serial communication protocols for their physical layers (typically RS485) and differ mainly in how data is encoded, RTU being more efficient and ASCII being somewhat more readable.
The KNET-CO2 supports Modbus ASCII & RTU only via RS-485.

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KNET-CO2 User's Manual
Network Topology
The KNET-CO2 uses RS-485 as its physical transport layer. Individual network elements are connected with a single twisted-pair of conductors, often covered by a metal shield. All network elements are wired in a `daisy chain' configuration as shown in Figure 1. Only the units at the ends of the chain have a terminating resistor connected between the two data lines.

Figure 1: BACnet Network Topology
Top: Properly routed network with no stubs and EOL termination only at the two ends of the network. Bottom: Improperly routed network with branch and stub connections as well as
improper termination (both enabled mid-chain and disabled at the terminals).

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KNET-CO2 User's Manual
NEARcom
NEARcom is a free app for Android (Android 14 or later) and Apple (iPhone 7 or later) phones equipped with near-field communication (NFC). NEARcom creates a virtual front panel for the KNET-CO2 on a smart phone, and allows the user to view and make changes to the device's settings. Using the NEARcom app is simple and intuitive: the user simply launches the app and briefly holds the phone near the front of the KNET-CO2 to read the device's current settings. After reading the KNET-CO2, the user can take the phone away from the device to view and make any desired changes to the settings. After all setting adjustments are complete, the user briefly holds the phone near the front of the KNET-CO2 and the new settings are transferred back to the device. Changes to the KNET-CO2 using the NEARcom app can be made while the device is unpowered (prior to installation) or while the devices is powered and operating normally. Refer to the Configuration section for more detailed information.
Calibration
Although the dual-beam CO2 sensor does not need frequent calibration the KNET-CO2 supports a single-point calibration using 2000 ppm CO2, balance air or balance nitrogen calibration gas. Calibration gas is distributed compressed in cylinders with pressures above 100 psi. To create the low pressure, weak flow gas stream fed to the CO2 sensor requires a pressure regulator that fits onto the cylinder supplying the calibration gas and delivers the low-pressure output stream into the ¼" OD plastic tubing that connects to the KNET-CO2's calibration nipple. This collection of apparatus, called a `calibration kit', is available from Kele.com under part number KCAL-2000. Accurate control of the flow rate of calibration gas into the sensor is essential for accurate calibration. A flow rate of 100 to 150 ml/min (milliliters/minute) is ideal. Significantly higher flow rates risk bursting the filter membrane at the sensor's diffusion port.

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Page 5

Specifications

KNET-CO2 User's Manual

Parameter

Value

Communication protocols BACnet MS/TP, Modbus RTU, Modbus ASCII

Supported baud rates

9600, 19200, 38400, 76800, 115200

Gas Sensor

Supervised, Dual-beam, non-dispersive infrared (NDIR)

Gas Sampling Method

0.5 micron filtered diffusion

Measurement Range

0-5000ppm

Repeatability

± 20 ppm CO2

Measurement Accuracy

Greater of: ± 50 ppm or ± 5% of reading

Calibration

One point, single gas calibration

Recommended Calibration Interval

5 years

Warm-up time

Initial readings within 15 seconds Full accuracy in 5 minutes

Power Requirements

15 - 40 VDC or 18 - 28 VAC RMS

Power Consumption

Less than 3 Watts

Operating Temperature Range

0 - 50° Celsius (32 122 F)

Operating Humidity Range

5 - 80% continuous; 0-95% intermittent [RH] non-condensing

Enclosure Dimensions

4.5" x 2.8" x 1.0" (116 x 72 x 25 mm) Wall mounting

Enclosure Material

White Satin Finish, thick wall ABS Plastic UL 94 V-O Flammability Rated

Relay

SPDT, Dry contact, Max rating 2A at 24VDC or 24VAC

Warranty

3-year for sensor, 7-year for electronics

Table 1: KNET-CO2 Specifications.

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KNET-CO2 User's Manual

Installation

Mechanical

The KNET-CO2 mounts most

conveniently onto a standard single-gang

electrical box, with wiring entering the

enclosure through the access opening in

its base. The same mounting holes can

be used to affix the KNET-CO2 onto any

flat vertical surface with appropriate fasteners.

Figure 2: Case Dimensions (mm &[in]).

The unit is specified for vertical mounting as shown in Figure 2, but will function, at only

slightly degraded accuracy, in any orientation.

Wiring

Feed wires through the enclosure base, then mount

the base onto a junction box or directly to the wall.

Connect wires to screw terminals on the circuit board

as shown in Figure 3. The screw terminal

connectors are removable for easy wire landing and

keyed so that they can only be inserted back into the

correct socket in the correct orientation.

Align the slots in the cover with the tabs on the base

and snap enclosure cover closed. Back the set screw (on the bottom of the cover) out to secure enclosure cover using a 3/32" Allen wrench.

Figure 3: Attaching to single gang box.

Power

The KNET-CO2 is typically powered from a polarized, nominal 24 VAC source. One side of the supply is be tied to earth ground. This lead is designated common, often a white wire and nomenclated as `COM' or just `C'. The other power supply lead is often a red wire labeled `HOT' or just `H'. It is critically important that all network devices are powered with the `HOT' power lead connected to the `HOT' power terminal and the `COM' lead to the `COM' terminal.
For installations without low-voltage operating power, or power of uncertain polarity, the simplest and safest solution is to connect each unit to its own power-line-driven, Class 2, 24 VAC step-down transformer. The secondary must be earth grounded, identified as the `common' lead and connected to the `COM' terminal of the unit as shown in Figure 4.

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KNET-CO2 User's Manual

Relay
The Single-pole double-throw (SPDT) relay connection terminals are shown in Figure 4 This is a low-voltage pilot-relay DO NOT CONNECT TO LINE VOLTAGE. When the relay is inactive the common (COM) terminal will be connected to the normally closed (NC) terminal and the normally open (NO) terminal will not be connected.
When the relay is active the common terminal will be connected to the normally open (NO) terminal and the normally closed (NC) terminal will not be connected.

Network Connection

The network (BACnet or Modbus) data lines should be

connected in a daisy chain configuration with no stubs

or branches as shown in Figure 1.

The RS-485 network uses a 3-conductor data

interconnection: a twisted-pair (A- and B+) and a

metallic shield. The twisted-pair conductors are not

identical and must not be confused with each other during installation.
In all installations (except for the last unit on the

Figure 4: Wiring diagram showing connections

current segment) there will be an incoming and an outgoing data pair and their shield or drain

wires.

It is critical that both incoming and outgoing A- conductors are connected to the A-

terminal, and both incoming and outgoing B+ conductors to the B+ terminal.

If the unit being installed is the last one on the segment (i.e. there are only single A- & B+ wires) the end-of-line resistor should be enabled by setting the EOL jumper (see Figure 5) to the EOL position with the shorting block on the left.

Only the end devices in the daisy chain should have EOL termination enabled.

The shield connection terminal is provided for convenience in connecting the cable shields or

drain wires together. The shield is not electrically connected to the KNET-CO2 and using the

connector to couple the shields is optional, but electrically connecting the two shields or

drain wires is absolutely required. The shield is left floating at the end unit.

The shield for the entire segment should be tied to ground only at a single end-point, typically the BAS.

Do Not connect the shield to the `COM' terminal.

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Figure 5: Data line termination jumper LEFT: EOL termination enabled RIGHT: EOL termination disabled

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Page 8

Configuration

KNET-CO2 User's Manual

Figure 6: Links to download NEARcom app.

Because of the relatively complex setup required to configure a networked sensor, the configuration is done through a graphical user interface (GUI) on an Android (Android 14 or later) and Apple (iPhone 7 or later) phone running the NEARcom configuration app. The free apps can be downloaded from the Google Play or Apple App stores using the QR codes in Figure 6.
NEARcom

The NEARcom app uses Near Field Communication (NFC) technology to provide a shortrange "touch" link with a mobile device to allow configuration, monitoring and adjustment of the KNET-CO2. Its settings are transferred to the phone by touching the phone to the front cover (with the middle-back of the phone near the area indicated in Error! Reference source n ot found.8). After the transfer is acknowledged, the phone can be taken away so the current configuration settings can be reviewed and changes made while holding the phone in a comfortable position. After making changes the phone is placed near the antenna again to transfer the changes to the KNET-CO2 (refer to the blow procedures for more information).

The configuration settings can be reviewed and changed while the KNET-CO2 is unpowered, allowing the device to be configured, unpowered, on the bench, prior to installation.

Inspecting the KNET-CO2 Settings

Before proceeding, download and install the NEARcom app from the Apple App-Store or from the Google Play Store (QR codes in Figure 6).

1. If an Android phone is being used, ensure NFC is turned on: refer to the phone's manual for more information.

Figure 7: Approximate location of the NFC antenna

2. Locate and launch the NEARcom app; the app will display "Read settings to make configuration changes."

3. Press the "Read" button located at the top of the app; the app will instruct the user to hold the phone over the KNET-CO2.

Hold the middle-back of the phone near the area indicated in Error! Reference source not f ound.8. After the transfer is complete, the phone can be moved away from the KNET-CO2, and the app will display all of the KNET-CO2 current settings.

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KNET-CO2 User's Manual
Configuring the Device Settings
1. Follow the steps outlined in Inspecting the KNET-CO2 Settings section above. No setting configurations are allowed until the current device settings have first been retrieved. Locate the setting to be adjusted. Select a setting by touching it, then make the desired changes: multiple settings can be changed before transferring them back to the KNETCO2. When settings are changed, their fields will be highlighted to indicate they will be updated during the next Write transfer
2. Press the "Write" button located at the top of the app: the app will display a message instructing the user to hold the phone over to the KNET-CO2 to transfer the new settings. NOTE: the "Write" button will be grayed out and inactive until a change to the settings have been made.
3. Place the middle-back of the phone over the area indicated in Figure 7 and hold it in this location until the prompt is removed.
NOTE: moving the phone away from the KNET-CO2 too early will abort transferring the new setting and an error message will be displayed. If this occurs, dismiss the error message, place the phone over the KNET-CO2 and hold it place until the transfer is complete.

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KNET-CO2 User's Manual

Network Parameter

Value

Description

Both

Baud Rate
Communication Mode

9600, 19200, 38400, 76800, 115200

Network Communication speed

BACnet, Modbus

Network type selection

MSTP Address 0 to 127

Must be unique in its MSTP segment and less than or equal to the value of
MSTP Maximum Master

Maximum Master

1 to 127

Must be greater than or equal to MSTP Address

BACnet

Device Instance Device Name

1 to 4194302
Limited to 50 characters

Must be unique in the entire network
Text field for user input of a device name (not required can be blank).

Device Location

Limited to 50 characters

Text field for user input describing the device's location (not required).

Device Description

Limited to 50 characters

Text field for user input describing the device (not required).

Modbus Mode

RTU, ASCII

Transmission mode of network messages

Modbus

Modbus Address

1 to 247

Must be unique on the subnet

Modbus Parity

Even, Odd, None

Communication parity bit. Setting must match other units.

Table 2: Configuration parameters for BACnet and Modbus networks

Device Config. Parameters

Value

Description

Relay Control Method

Remote or
Setpoint

Remote: the network has control of the KNETCO2 relay actuation.
Setpoint: the KNET-CO2 has control of relay actuation based on the value of CO2 Alarm Setpoint.

CO2 Alarm Setpoint

0 to 5000 ppm

The KNET-CO2 relay will actuate when the CO2 concentration rises above this setting (refer to Relay in the Operation section for more details).

Table 3: KNET-CO2 Configuration Parameters

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KNET-CO2 User's Manual
Configuration Procedure
Before beginning the configuration process:
1. Determine and record the parameter values needed for your installation: a list of the parameters for a BACnet or Modbus network is shown in Table 2.
2. Determine how the KNET-CO2 relay will be controlled (refer to Table 3 for more information).
NOTE: All KNET-CO2 network parameters for any previously configured units can quickly be determined; refer to Inspecting the KNET-CO2 Settings in the Configuration section of this manual.
Example configuration BACnet
For this example, the KNET-CO2 is being configured while it is unpowered (prior to installation). The process is the same if the KNET-CO2 is powered; however, the installer should ensure the MSTP Address and Device Instance are unique before the KNET-CO2 is attached to an existing network.
1. Launch the NEARcom app and read the current settings by pressing the Read button at the top of the screen and holding the phone near the KNET-CO2 (refer to Inspecting the KNET-CO2 Settings in the Configuration section of this manual). No setting changes can be made until this step is complete.
2. Touch Baud Rate and set this parameter to the value used by the rest of the network (9600, 19200, 38400, 76800, or 115200).
3. Set the Communication Mode parameter to BACnet: the NEARcom app will display only the parameters specific to BACnet.
4. Set the MSTP Address to the desired value This address is the physical-layer address that identifies the KNET-CO2 being installed to the network and must be unique to the MSTP network segment.
5. Set the Maximum Master parameter to the desired value. It must be set to a value greater-than or equal to the highest MSTP address that will be used on this MSTP segment (trunk) to which the device is connected. Caution: setting max master too low may result in nodes which are unable to communicate. If in doubt max master should be set to 127.
6. Set the Device Instance to a unique value for the entire BACnet network (value ranges from 0 to 4194302).
7. Select and enter the desired text for Device Name, Device Location, and Device Description parameters. These parameters can be left empty or contain up to 50 characters.
8. Select desired setting for Relay Control Method (Remote or Setpoint). If using Setpoint, enter a value the for CO2 Alarm Setpoint parameter (refer to Table 3).
9. Transfer the new settings to the KNET-CO2 by pressing the Write button at the top of the screen, then hold the phone near the KNET-CO2 until the setting are completely transferred. Refer to Configuring the KNET-CO2 Settings section in this manual for more details.
SETTINGS ARE NOT TRANSFERRED TO THE KNET-CO2 UNTIL THIS STEP IS COMPLETED AND A SUCCESS DIALOG IS SHOWN.

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KNET-CO2 User's Manual
Example configuration Modbus
For this example, the KNET-CO2 is being configured while it is unpowered (prior to installation). The process is the same if the KNET-CO2 is powered; however, the installer should ensure the Modbus Address is unique before the KNET-CO2 is attached to an existing network.
1. Launch the NEARcom app and read the current settings by pressing the Read button at the top of the screen and holding the phone near the KNET-CO2 (refer to Inspecting the KNET-CO2 Settings in the Configuration section of this manual). No setting changes can be made until this step is complete.
2. Touch Baud Rate and set this parameter the value used by the rest of the network (9600, 19200, 38400, 76800, or 115200).
3. Set the Communication Mode parameter to Modbus: this will cause all Modbus specific parameters to be shown and all of the BACnet specific parameters are hidden.
4. Select the Modbus Mode that is being used by the rest of the network (RTU or ASCII).
5. Set the Modbus Address of the device being installed (1 through 247). This address is the physical layer address and must be unique to prevent multiple devices from attempting to respond to queries.
6. Select the Modbus Parity setting that the rest of the network is using (Even, Odd, or None).
7. Select desired setting for Relay Control Method (Remote or Setpoint). If using Setpoint, enter a value the for CO2 Alarm Setpoint parameter (refer to Table 3).
8. Transfer the new settings to the KNET-CO2 by pressing the Write button at the top of the screen, then hold the phone near KNET-CO2 until the setting are completely transferred. Refer to Configuring the KNET-CO2 Settings section in this manual for more details.
NOTE: Settings are NOT changed within the KNET-CO2 until this step 8 is complete. If desired, the new settings can be verified directly after they have been transferred to the KNET-CO2 by following steps outlined in the Inspecting the KNET-CO2 Settings section of the manual.

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KNET-CO2 User's Manual
Operation
Relay
The relay can be controlled by two different mechanisms, setpoint control based on the CO2 reading or network control (default). When the relay is driven based on the setpoint it will be inactive as long as the CO2 concentration is below the setpoint threshold + the hysteresis value (10 ppm). Once active the relay will not transition to the inactive state until the CO2 concentration of the space falls below the setpoint threshold minus the hysteresis value. Under network control the relay state is irrevocably commanded by the network and is not responsive to local CO2 concentration (unless commanded to be so by the network). The operating mode of the relay is determined solely by the network. The mechanism of network relay control varies based on which communication protocol is being used; if BACnet is enabled the device controls the relay based on the binary output object using a priority array, if Modbus is enabled then the relay is driven based on the `Relay state' register.
CO2 Sensor
There is a 10s delay at startup before readings are available, during this time the CO2 will read 0 ppm. If setpoint control is enabled the relay will be inactive during startup to allow time for the CO2 sensor to initialize. The CO2 reading is updated once every second.
Sensor Supervision
The proper operation of the sensor is continually monitored by its internal supervision functionality. The following network properties are set should a sensor failure be detected.

BACnet

Reliability property of Analog Input 1: unreliable other Status_Flags property of Analog Input 1: `fault bit' is SET

Modbus

Table 4: Out of Service notification. The unit is declared out of service during calibration

or if sensor fails.

BACnet
A complete list of the objects available on the KNET-CO2 is available starting on page 18.
The device will initiate a single i-am after power-up to enable faster device discovery but otherwise will not initiate any network traffic (except token passing and polling for masters) without being queried.
If supporting hardware, such as the relay, is not present then the Reliability property for the corresponding object will indicate this.
None of the objects support event state reporting and Event State for all objects will always read Normal (0).

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KNET-CO2 User's Manual

Modbus

The KNET-CO2 uses either Modbus RTU or ASCII and supports even, odd, and no parity. The default settings are Modbus RTU with even parity.

Each frame is formatted based on settings as shown below in Table 5.

Mode Setting

Parity Setting

Start Bits

Data Bits Parity Bits Stop Bits

Even

RTU

Odd

None

ASCII

Even

Odd

None

Table 5: Modbus Data Formatting

The register table is available on Table 6 on page 22. All registers are modeled as holding registers. If a register is listed as read-only then any attempts to write to the register will receive an error response.
Registers can be read with function code 3 (read holding register) and written with function code 6 (write single register). Attempts to write to a read-only register will receive an error response with exception code 4.
The mode, parity, device address, and baud rate are set using the NEARcom configuration application.

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KNET-CO2 User's Manual

Calibration

During calibration the KNET-CO2 Analog Input object's reliability will be set as shown in Table 4. During the calibration, the relay will be in an inactive state even if the CO2 is above the setpoint.
Calibration requires a calibration kit with calibration grade 2000 ppm CO2, balance air or nitrogen gas, available from KELE as part number KCAL-2000. Assemble its gas delivery components as shown in Figure 8.
Figure 9 shows the location of the KNET-CO2's calibration port. Insert the ¼ inch OD gas delivery tube through it and over the calibration nipple of the sensor inside.

Figure 8: Calibration Gas Delivery Apparatus:

No changes are made until the calibration is confirmed during step 5; if an error is made during the process, remove and reconnect the KNET-CO2's power to abort the calibration.
Calibration Procedure

1. Temporarily remove the dust cover from the calibration gas port on the bottom of the enclosure cover.
2. Pass the 1/4" OD calibration gas tube into the `Calibration Gas Port' and slide onto the fitting inside. Enable calibration gas flow by turning the regulator knob a half-turn counter-clockwise (see Figure 8).

3. Allow calibration gas to flow for one minute, then use a 1/16" Allen wrench (or equivalent) to depress the "CO2 Calibration Activator" switch for 5 seconds until the LED blinks yellow.
4. After a few minutes the LED will blink green. The calibration process is completed.

Figure 9:Calibration landmarks

5. Remove calibration gas tube from case and ensure that the `hiss' of flowing gas can still be heard.
If gas flow is NOT DETECTED the KNET-CO2 has very likely been mis-calibrated. Briefly disconnect the unit's power to abort the calibration. Replace the calibration gas cylinder and repeat the process starting at step 2.

6. If gas is still flowing, press and hold the calibration button to accept and save the calibration. The LED will turn solid green, indicating that calibration is complete. If the calibration process is not confirmed within 5 minutes after the LED turns green in step 4, the unit will abandon the calibration and return to normal operation with the calibration unchanged.

7. Disable gas flow by turning the regulator knob fully clockwise, and remove gas tubing from the calibration port.

8. Replace the dust cover on the gas calibration port.

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Page 16

Disclaimers
Life Safety

KNET-CO2 User's Manual

This KNET-CO2 is not designed, certified, sold or authorized for use in applications where failure of this device could be reasonably expected to
result in personal injury or death.

Warranty
Kele warrants to Buyer that for the duration stated in Table 1 (on page 6) from the date of shipment of Products to the Buyer that Products will substantially conform to the product specifications agreed to by Kele. This warranty is not transferable.
This warranty does not cover: Defects due to misuse, abuse, or improper or inadequate care, service or repair of Products; Defects due to modification of Products, or due to their alteration or repair by anyone other than Kele; Problems that arise from lack of compatibility between Kele Products and other components used with those Products or the design of the product into which Products are incorporated. Buyer is solely responsible for determining whether Products are appropriate for Buyer's purpose, and for ensuring that any product into which Products are incorporated, other components used with Kele's Products, and the purposes for which Kele's Products are used are appropriate and compatible with those Products.
Unless Kele agrees otherwise, to obtain service under this warranty, Buyer must pack any nonconforming Product carefully, and ship it, postpaid or freight prepaid, to Kele, Inc. at 3300 Brother Boulevard Memphis, TN 38133 before the expiration of the warranty period shown in Table 1. Buyer must include a brief description of the nonconformity. Any actions for breach of this warranty must be brought within one year of the expiration of this warranty.
If Kele determines that a returned Product does not conform to this warranty it will, at its sole discretion, either repair or replace that Product, and will ship the Product back to Buyer free of charge. At Kele's option, Kele may choose to refund to Buyer the purchase price for a nonconforming Product instead of repairing or replacing it.

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KNET-CO2 User's Manual

Appendix 1: BACnet objects and default values
Device Object

Property

Default

Access permissions

Object_Identifier Object_Name Object_Type System_Status Vendor_Name Vendor_Identifier Model_Name Firmware_Revision Application_Software_Version Location Description Protocol_Version Protocol_Revision Protocol_Services_Supported
Protocol_Object_Types_Supported
Object_List
Max_APDU_Length_Accepted Segmentation_Supported APDU_Timeout Number_Of_APDU_Retries Max_Master Max_Info_Frames Device_Address_Binding

(device, 283000) KNET-CO2 8 : Object Device 0 : Operational Kele, Inc. 283 KNET-CO2 v2.0.2 v2.0.2 "": empty string CO2 sensor 1 14 ReadProperty, WriteProperty, DeviceCommunicationControl, WhoHas, Who-Is analog-input, analog-value, binaryoutput, binary-value, device {(device, 283000), (analog-input, 1), (binary-output, 1), (analog-value, 1), (binary-value, 1)} 480 3 : None 10000 0 127 1 {}

Read / Write Read / Write Read Read Read Read Read Read Read Read / Write Read / Write Read Read Read
Read
Read
Read Read Read Read Read / Write Read Read

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Property
Database_Revision Property_List

KNET-CO2 User's Manual

Default
1
{system-status, vendor-name, vendoridentifier, model-name, firmwarerevision, application-software-version, protocol-version, protocol-revision, protocol-services-supported, protocolobject-types-supported, object-list, max-apdu-length-accepted, segmentation-supported, apdu-timeout, number-of-apdu-retries, max-master, max-info-frames, location, description, device-address-binding, databaserevision}

Access permissions
Read
Read

CO2 - Analog Input Object 1

Property
Object_Identifier Object_Name Object_Type Present_Value
Status_Flags Event_State Reliability Out_Of_Service Units Property_List

Default
(analog-input, 1) Carbon Dioxide 0 : Object Analog Input Current value from sensor
{F,F,F,F} 0 : Normal 0 : No Fault Detected False 96 : Parts Per Million {present-value, status-flags, event-state, reliability, out-of-service, units}

Access permissions
Read Read Read Write (only when Out_Of_Service is True) / Read Read Read Read Write / Read Read Read

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KNET-CO2 User's Manual
Relay Binary Output Object 1

Property
Object_Identifier Object_Name Object_Type Present_Value Status_Flags Event_State Reliability Out_Of_Service Polarity Inactive_Text Active_Text Priority_Array
Relinquish_Default Property_List

Default

Access permissions

(binary-output, 1) Relay 4 : Object Binary Output False {F,F,F,F} 0 : Normal 0 : No Fault Detected False 0 : Normal Inactive Active {Null, Null, Null, Null, Null, Null, Null, Null, Null, Null, Null, Null, Null, Null, Null, Null} False {present-value, status-flags, event-state, reliability, out-ofservice, polarity, inactive-text, active-text, priority-array, relinquish-default}

Read Read Read Read / Write Read Read Read Read / Write Read Read Read Read
Read / Write Read

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Relay Setpoint - Analog Value Object 1

Property

Default

Access permissions

Object_Identifier Object_Name Object_Type Present_Value Status_Flags Event_State Out_Of_Service Units Property_List

(analog-value, 1) Relay Setpoint 4 : Object Binary Output 1000 {F,F,F,F} 0 : Normal False 96 : Parts Per Million {present-value, status-flags, event-state, out-of-service, units}

Read Read Read Read / Write Read Read Read Read Read

Enable Local Relay Control - Binary Value Object 1

Property

Default

Object_Identifier Object_Name Object_Type Present_Value Status_Flags Event_State Out_Of_Service Inactive_Text
Active_Text
Property_List

(binary-value, 1) Enable Local Relay Control 5 : Object Binary Value inactive {F,F,F,F} 0 : Normal False BACnet relay control based on the relay present value (Binary Output 1) Local relay control based on the setpoint present value (Analog Value 1) {present-value, status-flags, event-state, out-of-service, inactive-text, active-text}

Access permissions
Read Read Read Read / Write Read Read Read Read
Read
Read

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Appendix 2: Modbus registers
Register Name

Type

Units

Access Permissions

4001

CO2 Status

uint16

See table below

Read

4002

CO2 Reading

uint16

ppm

Read

4003

Enable relay setpoint control

Bool

enable=1 / disable=0

Read / Write

4004

Relay state

Bool

on=1 / off=0

Read / Write

4005

Relay setpoint

uint16

ppm

Read / Write

Table 6: Modbus Registers. The leading '4' is by convention to indicate holding register and is not sent to the device.

Status code Description

Normal operation

No sensor present

No relay present

Sensor fault (during normal

operation) or calibration ongoing

(during calibration process)

Internal communication error

Table 7. Possible values for Modbus CO2 status register (register 4001).

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KNET-CO2 User's Manual
Appendix 3: 3rd Party Software Components & Licenses
The following components are used in the software of this device.
FreeModbus - https://www.embedded-experts.at/en/freemodbus/ Licensed under BSD 3-Clause license, text available at https://github.com/cwalterat/freemodbus/blob/master/bsd.txt
FreeRTOS - https://www.freertos.org/ Licensed under MIT license, text available at https://www.freertos.org/a00114.html
JSMN - https://zserge.com/jsmn/ Licensed under MIT license, text available at https://github.com/zserge/jsmn/blob/master/LICENSE
STM HAL - https://github.com/STMicroelectronics/stm32g0xx_hal_driver Licensed under BSD 3-Clause license, text available at https://github.com/STMicroelectronics/stm32g0xx_hal_driver/blob/master/License.md

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Date 12/16/2024

KNET-CO2 User's Manual
REVISION HISTORY
Comments Preliminary release as 90-0018-0a

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References

Microsoft Word for Microsoft 365