Modbus PTV [EIA-485] Interface for
Toshiba air conditioners
Compatible with Digital Inverter & VRF lines

USER MANUAL
Issue date: 04/2019 r2.7 ENGLISH

Modbus RTU (EIA-485) Interface for Toshiba air conditioners Compatible with Digital Inverter & VRF lines

Important User Information

Disclaimer

The information in this document is for informational purposes only. Please inform HMS Industrial Networks of any inaccuracies or omissions found in this document. HMS Industrial Networks disclaims any responsibility or liability for any errors that may appear in this document.

HMS Industrial Networks reserves the right to modify its products in line with its policy of continuous product development. The information in this document shall therefore not be construed as a commitment on the part of HMS Industrial Networks and is subject to change without notice. HMS Industrial Networks makes no commitment to update or keep current the information in this document.

The data, examples, and illustrations found in this document are included for illustrative purposes and are only intended to help improve understanding of the functionality and handling of the product. In view of the wide range of possible applications of the product, and because of the many variables and requirements associated with any particular implementation, HMS Industrial Networks cannot assume responsibility or liability for actual use based on the data, examples, or illustrations included in this document nor for any damages incurred during the installation of the product. Those responsible for the use of the product must acquire sufficient knowledge in order to ensure that the product is used correctly in their specific application and that the application meets all performance and safety requirements including any applicable laws, regulations, codes, and standards. Further, HMS Industrial Networks will under no circumstances assume liability or responsibility for any problems that may arise as a result of the use of undocumented features or functional side effects found outside the documented scope of the product. The effects caused by any direct or indirect use of such aspects of the product are undefined and may include e.g. compatibility issues and stability issues.

Presentation

The INMBSTOS001R000 interfaces allow complete and natural integration of Toshiba air conditioners into Modbus RTU (EIA-485) networks.
Compatible with Digital Inverter & VRF lines. Reduced dimensions.
93 x 53 x 58 mm
3.7” x 2.1” x 2.3”

• Quick and easy installation.
  Mountable on DIN rail, wall, or even inside the indoor unit of AC.
• External power is not required.
• Direct connection to Modbus RTU (EIA-485) networks. Up to 63 INMBSTOS001R000 devices can be connected to the same network.
  INMBSTOS001R000 is a Modbus slave device.
• Direct connection to the AC indoor unit. Up to 16 AC indoor units can be connected to INMBSTOS001R000, controlling them as one (not individually).
• Configuration from both on-board DIP switches and Modbus RTU.
• Total Control and Supervision.
• Real states of the AC unit’s internal variables.
• Allows simultaneous use of the AC’s remote controls and Modbus RTU.

* Up to 63 Intesis devices can be installed in the same Modbus RTU bus. However, depending on the configured speed, the installation of Modbus Repeaters may be required

Connection

The interface comes with a plug-in terminal block of 2 poles to establish a direct connection with the AC indoor unit. It comes as well with a plug-in terminal block of 2 poles to establish a direct connection with the Modbus RTU EIA-485 network.

Connect to the AC indoor unit

The INMBSTOS001R000 connects directly to the Toshiba AB Bus, which is not provided within the interface. The recommended connection’ methods are the following ones  (details in Figure 2. 1):

• Wired remote control available.
• No remote control is available

Maximum AB bus length is 500 m / 1,640.42 ft. The bus has no polarity sensitivity.

Important: If a wired remote controller of the AC manufacturer is connected to the same bus, communication may shut down.

Figure 2. 1 ,INMBSTOS001R000 connection diagram

Connection to the EIA-485 bus

Connect the EIA-485 bus wires to the plug-in terminal block of INMBSTOS001R000 and keep the polarity on this connection (A+ and B-). Make sure that the maximum distance to the bus is 1,200 meters (3,937 ft). Loop or star typologies are not allowed in the case of the EIA-485 bus. A terminator resistor of 120Ω must be present at each end of the bus to avoid signal reflections. The bus needs a fail-safe biasing mechanism (see section 4.7 for more details).

Quick Start Guide

1. Disconnect the air conditioning from the Mains Power.
2. Attach the interface next to the AC indoor unit (wall mounting) following the instructions of the diagram below or install it inside the AC indoor unit (respect the safety instructions given).
3. Connect the AB bus between the interface and the AC indoor unit following the instructions of the diagram. Screw each bare cable end in the corresponding AB terminals of each device.
4. Connect the EIA-485 bus to the connector EIA485 of the interface.
5. Close the AC indoor unit. 6. Check the DIP-Switch configuration of the Intesis interface and make sure it matches the current installation’s parameters (see section 4.4).

By default, the interface is set to:

▪ Modbus Slave Address ➔ 1
▪ Modbus baud rate ➔ 9600 bps

These parameters can be modified from SW4 and SW3 DIP-Switches.
All other switch positions are set at a low level (Off position) by default.
NOTE: All changes on the DIP-Switch configuration require a system power cycle to be applied.

7. Connect the AC system to Mains Power.
IMPORTANT: The Intesis interface requires to be connected to the AC unit (powered) to start communicating.

Modbus Interface Specification

Modbus physical layer

INMBSTOS001R000 implements a Modbus RTU (Slave) interface, to be connected to an EIA-485 line. It performs 8N2 communication (8 data bits, no parity, and 2 stop bit) with several available baud rates (2400 bps, 4800 bps, 9600 bps -default-, 19200 bps, 38400 bps, 57600 bps, 76800 bps, and 115200 bps). It also supports 8N1 communication (8 data bits, no parity, and 1 stop bit).

4.2 Modbus Registers

All registers are type “16-bit unsigned Holding Register” and they use the Modbus big-endian notation.

4.2.1 Control and status registers

1. Available values will depend on the AC unit mode. Check the AC unit model functions in its user manual to know the possible values for this register.
2. The magnitude for this register can be adjusted to Celsius x 1ºC, Celsius x 10ºC (default), or Fahrenheit. See section 4.3.6 for more information.
3. It is not possible to turn to x10 the value shown in Fahrenheit.

4 . This value is stored in non-volatile memory
5. See section 7 for possible error codes and their explanation
6. See section 4.3.6 for more information
7. If the register is configured as “0:Non-blocked”, all commands received from Modbus will be sent to the AC system. If “1: Blocked”, commands from Modbus will only be sent to the AC system if they differ from the previous value.
8. This register applies to firmware version 2.3 onwards

4.2.2 Configuration Registers

While the initialization is ongoing, some Modbus registers indicate an undetermined value. Once the normal operation starts, they acquire its corresponding value. It is important to keep in mind that any change done during the initialization process will not have effect until it has been finished.

4.3 Modbus Registers for Advanced Functions

4.3.1 Advanced registers for Indoor Unit status

These registers are only available when the indoor unit’s type selected on SW1 is different from the default value. Please, check the Section 4.4 for more information.

NOTE: IU stands for Indoor Unit’s Index

9. Once window contact is open, a count-down to switch off the AC Unit will start from this configured value.
10. The range 38400bps-115200bps applies to firmware version 2.3 onwards

4.3.2 Advanced registers for Outdoor Unit Status on VRF-SMMSi Systems

These registers are only available when the indoor unit’s type selected on SW1 is different from the default value. Please, check section 4.4 for more information.

4.3.3 Advanced registers for Outdoor Unit Status on VRF-SHRM/SMMS Systems

These registers are only available when the indoor unit’s type selected on SW1 is different from the default value. Please, check section 4.4 for more information

4.3.4 Advanced registers for Outdoor Unit Status on RAV Systems

These registers are only available when the indoor unit’s type selected on SW1 is different from the default value. Please, check section 4.4 for more information

4.3.5 Advanced registers for Indoor Unit Type and Refresh Time adjustment

This parameter indicates the cadence when reading priority signals. Priorities are defined as follows and can’t be modified:

0: Update on start-up

1. High priority
2. Low priority

The higher the value, the fastest the priority signals are going to update. The cadence is defined by:

• One high priority signal and one low priority signal’s poll.
• Two high-priority signals and one low-priority signal’s poll.
• Three high-priority signals and one low-priority signal’s poll.
• Four high-priority signals and one low-priority signal’s poll.

4.3.6 Considerations on Temperature Registers

• AC unit temperature setpoint (R/W)
  (register 4 – in Protocol address / register 5 – in PLC address):
  This is the adjustable temperature setpoint value that must be required by the user.
  This register can be read (Modbus function 3 or 4) or written (Modbus functions 6 or 16). A remote controller connected to the Toshiba indoor unit will report the same temperature setpoint value as this register.

• AC unit temperature reference (R)
  (register 5 – in Protocol address / register 6 – in PLC address):
• This register reports the temperature that is currently used by the Toshiba indoor unit as the reference of its own control loop.
  If the value on the register 22 is valid (different from 0x8000), it will report the value from this register. If not, it will show the indoor unit reference temperature.
  It is a read-only register (Modbus functions 3 or 4).
  Depending on the mode selected, the register shows a different value:
  Heat Mode:
  Temperature reference = Ambient temperature +0.5⁰C
  Dry Mode / Fan Mode / Cool mode:
  Temperature reference = Ambient temperature -0.5⁰C
  When the mode changes from Heat to anyone else, or from anyone else to Heat, the register updates the value using the intervals +0.5°C/-0.5°C

• AC unit external temperature reference (Modbus) (R/W)
  (register 22 – in Protocol address / register 23 – in PLC address):
  This register reports the temperature from an external sensor in the Modbus side. If valid value is received, the Modbus register will indicate a 0x8000 value.
  This register can be read (Modbus function 3 or 4) or written (Modbus functions 6 or 16).

• AC Real temperature setpoint (R)
  (register 23 – In Protocol address / register 24 – in PLC address):
  This register will show the same value as in register 4 (protocol address). The reference temperature from the remote controller is sent directly to the AC unit to be applied in the control loop.
  It is a read-only register (Modbus functions 3 or 4).
  Moreover, notice that temperature’s values of all these four registers are expressed according to the temperature´s format configured through its onboard DIP-Switches (See “4.4 -DIP-switch Configuration Interface”). The following formats are possible:• Celsius value: Value in Modbus register is the temperature value in Celsius (i.e. a value “22” in the Modbus register must be interpreted as 22ºC)
  • Decicelsius value: Value in Modbus register is the temperature value in decicelsius (i.e. a value “220” in the Modbus register must be interpreted as 22.0ºC)
  • Fahrenheit value: Value in Modbus register is the temperature value in Fahrenheit (i.e. a value “72” in the Modbus register must be interpreted as 72ºF (~22ºC).

4.4 DIP-switch Configuration Interface

All the configuration values on INMBSTOS001R000 can be written and read from Modbus interface. Otherwise, some of them can also be setup from its on-board DIP-switch interface. The device has DIP-switches SW1, SW3 and SW4 on the following locations:

The following tables apply to the interface´s configuration through DIP-switches:
SW1 – AC indoor unit’s features

Table 4.1 SW1: AC indoor unit´s features

SW3/SW4 – Baud rate configuration

Table 4.2 SW3-SW4: Modbus baud rate

SW4 – Degrees/Decidegrees (x10), temperature magnitude (ºC/ºF), and EIA-485 termination resistor.

Table 4.3 SW4: Temperature and termination resistor configuration

SW3 – Modbus Slave address

Table 4.4 SW3: Modbus slave address

4.5 Implemented Functions

INMBSTOS001R000 implements the following standard Modbus functions:

▪ 3: Read Holding Registers
▪ 4: Read Input Registers
▪ 6: Write Single Register
▪ 16: Write Multiple Registers (Despite this function is allowed, the interface does not allow to write operations on more than 1 register with the same request, this means that the length field should always be 1 when this function is being used in case of writing)

4.6 Device LED indicator

The device includes two LED indicators to show all the possible operational states. In the following table there are written the indicators which can be performed and their meaning.

L1 (green LED)

L2 (red LED)

L1 (green LED) & L2 (red LED)

4.7 EIA-485 bus. Termination resistors and Fail-Safe Biasing mechanism

EIA-485 bus requires a 120Ω terminator resistor at each end of the bus to avoid signal reflections.

In order to prevent fail status detected by the receivers, which are “listening” the bus, when all the transmitters’ outputs are in three-state (high impedance), it is also required a fail-safe biasing mechanism. This mechanism provides a safe status (a correct voltage level) in the bus when all the transmitters’ outputs are in three-state. This mechanism must be supplied by the Modbus Master.

The INMBSTOS001R000 device includes an onboard terminator resistor of 120Ω that can be connected to the EIA-485 bus by using DIP-switch SW4. Some Modbus RTU EIA-485 Master devices can provide also an internal 120Ω terminator resistor and/or fail-safe biasing mechanism (Check the technical documentation of the Master device connected to the EIA-485 network in each case).

List of supported AC Unit Types.

A list of Toshiba indoor unit model references compatible with INMBSTOS001R000 and their available features can be found in:
intesis_inxxxtos001rx00_compatibility-list [PDF]

Error Codes

In case to detect an error code not listed, contact your closest Toshiba technical support service.

© HMS Industrial Networks S.L.U. – All rights reserved This information is subject to change without notice
URL https://www.intesis.com

Documents / Resources

Intesis Modbus RTU Interface for Toshiba Air Conditioners [pdf] User Manual Intesis, EIA-485

References

• User Manual