SignalFire A2 HART Interface Manual
SignalFire Model: A2-HART-XXXX
Product Features
The SignalFire A2-HART Node offers the following features:
- HART communication loop supporting up to 4 HART devices, reading up to 4 process variables from each.
- Provides 18VDC to the HART communication loop.
- One counter/frequency input, up to 2kHz, supporting open drain or pulse input.
- Reports the state of dry contact inputs (open/closed).
- One 32-bit count totalizer.
- Low power operation using a 3 "D" cell lithium battery pack or A2-HCSolar system. External power from 3.5 to 5.0VDC can be used.
- Sends data to a SignalFire Buffered Modbus Gateway.
- AES128bit Encryption.
Specifications
Enclosure Size: 7.0" tall × 4.25″ wide × 3.0″ deep (not including attached antenna)
Power Source: Internal Lithium battery pack (SignalFire Part Number: Bat-3XD) or Solar battery system (SignalFire Part Number: IQSB-2XD-Solar).
Temperature Rating: -40°C to +85°C
Radio Frequency: 500mW, 902-928MHz ISM Band, FHSS radio
Compliance: FCC Part 15 compliant radio
Connections and Components
Radio LEDs:
- Radio TX LED (green): Flashes with each sent radio packet. Blinks rapidly when searching for the radio network.
- Radio RX LED (red): Blinks on each received radio packet.
Status LEDs:
- Active LED (green): Blinks at boot up and rapidly when the sensor is being powered.
- ERROR LED (red): Blinks to indicate an error condition.
Scan/Check-in Button: Pressing this button applies power to the sensor for the configured sensor on time and initiates a scan for the HART sensor. If the HART sensor is detected, the HART_STATUS LED blinks once, and its data is read. The A2 also sends the collected sensor data to the gateway.
Setup
Nodes require setup before deployment. Configurable items include:
- Network selection
- Encryption Settings
- Check-in period selection
- Modbus Slave ID setting
- Sensor on time
Settings are configured using the SignalFire Toolkit PC application and a serial programming cable. Legacy devices with rotary and DIP switches can also use these switches for Modbus Slave ID setting.
Using the SignalFire Toolkit
The SignalFire Toolkit application can be downloaded from www.signal-fire.com/customer. After installation, launch the software. The main toolkit window allows for auto-detecting devices on a COM port.
Select the COM port associated with the A2 Node and click "Auto-Detect Device on COM Port." This opens the device configuration window for all device settings.
Network Setting
Network, network group, and Encryption Key/Corporate ID settings must match the gateway and other nodes for communication. For legacy devices with rotary switches, network is set using rotary switch SW2. If set to zero, the network can be set via the Toolkit software.
Encryption
Starting with A2 version r72, over-the-air transmissions can be encrypted to prevent tampering. Encryption keys replace the Corporate ID system. Ensure all devices connected to a Gateway share the same encryption key, network, and network group number.
To enable encryption on a node, check the "Enable Encryption" box within the "Set Corporate ID" section. This will prompt for an encryption key. Note that keys cannot contain spaces or angle brackets. Setting the key causes the node to drop its network and only join networks with the same encryption key. For new networks, set the encryption key on all devices. For legacy networks, setting the Corporate ID without enabling encryption maintains compatibility.
Encryption keys can be made unrecoverable via the "Settings" menu for enhanced security. However, forgetting the key requires resetting it on every device.
Modbus Slave ID
The Modbus Slave ID can be set using the SignalFire Toolkit or the DIP switch on legacy devices. The DIP switch uses an 8-bit binary input for slave IDs 1-240. The least significant bit (LSB) is on the right. The A2 requires a power cycle after setting the DIP switch. To set the Slave ID via the SignalFire Toolkit, the DIP switch must be set to 0 (all switches off).
Sensor Settings
The A2-HART Node supplies 18 volts to the sensor. Sensor warm-up time is configurable; the default is 2 seconds, suitable for most sensors. Radar sensors may require longer warm-up times; consult the sensor manufacturer or SignalFire.
Check-In Interval
The check-in period is set using the SignalFire Toolkit. For legacy devices with rotary switch SW1, the check-in interval can be set directly. If SW1 is set to position 0, the interval is configured via the Toolkit. The table below shows switch settings and corresponding check-in periods:
| Switch Setting | Check-In Period |
|---|---|
| 0 | 1 min |
| 1 | 2 min |
| 2 | 4.5 min |
| 3 | 10 min |
| 4 | 30 min |
| 5 | 1 hr |
| 6 | 5 sec |
| 7 | 15 sec |
The default setting is 2, for a 4.5-minute check-in period. Settings 6 and 7 have high power draw and should only be used for testing or non-battery powered nodes.
HART Sensor Connections
HART sensors connect via the screw terminal connector on the daughterboard, using the two HART terminals.
Up to 3 additional HART sensors can be daisy-chained in parallel.
The system supplies a minimum of 18 Volts to sensors for 2 seconds (default). If 4 HART devices are connected, the total loop current is 16mA, resulting in a 4V drop across the 250 ohm load resistor, leaving 14V available for sensors.
Upon power-up, the A2-HART node polls for HART devices (addresses 1-4) to discover connected nodes. It reads the Manufacturer and device ID for each sensor and sends this to the gateway. The green LED (D6) blinks for each detected HART sensor (e.g., twice for ID 2, four times for ID 4).
To manually run the HART discovery process and force a check-in, press switch SW4. The discovery process re-runs every 100 check-ins.
Externally Powered HART Loop
For external power, remove jumper J3 from the HART card and set sensor on time to 0 seconds via the Toolkit. Connect HART+ and HART- terminals in parallel to HART devices. The 250ohm HART resistor must be installed in the loop, as the A2's internal resistor is bypassed.
HART Sensor Configuration
The A2 requires the attached HART sensor to be configured to HART ID 1, 2, 3, or 4 in "multi-drop" mode. Configuration can be done via a HART modem or the A2's built-in tools.
To set the HART ID, navigate to Tools > HART Sensor Configuration in the A2-HART Sensor Interface.
If the sensor is not set to "Sensor Always On," click the button to power the sensor for configuration. Each click powers the sensor for 5 minutes or until turned off. Wait for sensor warm-up before proceeding.
The "HART Sensor Configuration" window allows loop power control. To change the HART ID, first click "Scan" to find the current ID (defaults to 0). Then, select the existing ID on the left, choose the new ID (1-4) on the right, and click "Set." If only one HART device is connected, configure it as HART ID 1.
Digital Input
The counter input can be an open collector type (sinking ground), dry contact input, or voltage pulse (up to 15V) type, counting up to 2000 Hz.
Connection diagrams are provided for Open Collector, Voltage Pulse, and Dry Contact connections to the Radio Board.
Counts are stored in non-volatile memory. System resets revert counts to the last stored value. The system also reports the state of contact closure inputs at check-in.
Digital Input Debounce
To accurately totalize digital input counts, enable the digital input debounce timer in the SignalFire Toolkit (Settings > Digital Input Debounce). This is useful for dry contacts that might produce extra counts when closing. A typical debounce value for a dry contact is 100mS, ignoring counts due to contact bounce within this time.
Remote Modbus Register Mapping
The A2-HART sends data to a SignalFire Telemetry Modbus Gateway. Data is available at the gateway for reading via Modbus RTU. A unique Modbus slave ID is required for each node on the network, which the gateway uses to store data.
During each check-in, sensor data is read and sent to the gateway, stored in 16-bit registers under the set Modbus ID. If a HART device does not return all four variables, corresponding register values are set to 0.
Register Map
| Register Number | Register Address (Offset) | Description |
|---|---|---|
| 41004 | 1003 | Digital Input state (1=closed, 0=open) |
| 41005-41006 | 1004-1005 | 32-bit Hardware counter, 1004=high word |
| 41007 | 1006 | Average frequency over the last check-in period times 10 |
| 41012 | 1011 | Ave. counts per minute over the check-in period times 10 |
| 41013 | 1012 | Frequency over 2 seconds at check-in time times 10 |
| 42001 | 2000 | HART ID 1: Manufacturer's ID Code/Device Type (ID=MSB, Device=LSB) |
| 42002 | 2001 | HART ID 1: Device ID Number (ID high bite = MSB, ID mid byte = LSB) |
| 42003 | 2002 | HART ID 1: Device ID Number, HART Status (ID low byte=MSB, Status=LSB) |
| 42004 | 2003 | HART ID 1: PV & SV Units Code (PV=MSB, SV=LSB) |
| 42005 | 2004 | HART ID 1: TV & QV Units Code (TV=MSB, QV=LSB) |
| 42006-42007 | 2005-2006 | HART ID 1: Primary Variable (PV) (two registers) (float) |
| 42008-42009 | 2007-2008 | HART ID 1: Secondary Variable (SV) (two registers) (float) |
| 42010-42011 | 2009-2010 | HART ID 1: Tertiary Variable (TV) (two registers) (float) |
| 42012-42013 | 2011-2012 | HART ID 1: Quaternary Variable (QV) (two registers) (float) |
| 42014 | 2013 | HART ID 2: Manufacturer's ID Code/Device Type (ID=MSB, Device=LSB) |
| 42015 | 2014 | HART ID 2: Device ID Number (ID high bite = MSB, ID mid byte = LSB) |
| 42016 | 2015 | HART ID 2: Device ID Number, HART Status (ID low byte=MSB, Status=LSB) |
| 42017 | 2016 | HART ID 2: PV & SV Units Code (PV=MSB, SV=LSB) |
| 42018 | 2017 | HART ID 2: TV & QV Units Code (TV=MSB, QV=LSB) |
| 42019-42020 | 2018-2019 | HART ID 2: Primary Variable (PV) (two registers) (float) |
| 42021-42022 | 2020-2021 | HART ID 2: Secondary Variable (SV) (two registers) (float) |
| 42023-42024 | 2022-2023 | HART ID 2: Tertiary Variable (TV) (two registers) (float) |
| 42025-42026 | 2024-2025 | HART ID 2: Quaternary Variable (QV) (two registers) (float) |
| 42027 | 2026 | HART ID 3: Manufacturer's ID Code/Device Type (ID=MSB, Device=LSB) |
| 42028 | 2027 | HART ID 3: Device ID Number (ID high bite = MSB, ID mid byte = LSB) |
| 42029 | 2028 | HART ID 3: Device ID Number, HART Status (ID low byte=MSB, Status=LSB) |
| 42030 | 2029 | HART ID 3: PV & SV Units Code (PV=MSB, SV=LSB) |
| 42031 | 2030 | HART ID 3: TV & QV Units Code (TV=MSB, QV=LSB) |
| 42032-42033 | 2031-2032 | HART ID 3: Primary Variable (PV) (two registers) (float) |
| 42034-42035 | 2033-2034 | HART ID 3: Secondary Variable (SV) (two registers) (float) |
| 42036-42037 | 2035-2036 | HART ID 3: Tertiary Variable (TV) (two registers) (float) |
| 42038-42039 | 2037-2038 | HART ID 3: Quaternary Variable (QV) (two registers) (float) |
| 42040 | 2039 | HART ID 4: Manufacturer's ID Code/Device Type (ID=MSB, Device=LSB) |
| 42041 | 2040 | HART ID 4: Device ID Number (ID high bite = MSB, ID mid byte = LSB) |
| 42042 | 2041 | HART ID 4: Device ID Number, HART Status (ID high byte=MSB, Status=LSB) |
| 42043 | 2042 | HART ID 4: PV & SV Units Code (PV=MSB, SV=LSB) |
| 42044 | 2043 | HART ID 4: TV & QV Units Code (TV=MSB, QV=LSB) |
| 42045-42046 | 2044-2445 | HART ID 4: Primary Variable (PV) (two registers) (float) |
| 42047-42048 | 2046-2047 | HART ID 4: Secondary Variable (SV) (two registers) (float) |
| 42049-42050 | 2048-2049 | HART ID 4: Tertiary Variable (TV) (two registers) (float) |
| 42051-42052 | 2050-2051 | HART ID 4: Quaternary Variable (QV) (two registers) (float) |
| 42053 | 2052 | Bitmap of the Sensors Read in Last Check-in |
| 49987 | 9986 or 65523 | Low Battery Alarm (0 = battery above 3.0V, 1 = battery below 3.0V) |
| 49988 | 9987 or 65524 | Major revision number for the mainboard |
| 49989 | 9988 or 65525 | Minor revision number for the mainboard |
| 49990 | 9989 or 65526 | Major revision number for the radio |
| 49991 | 9990 or 65527 | Minor revision number for the radio |
| 49992 | 9991 or 65528 | High 16 bits of SFTS node address |
| 49993 | 9992 or 65529 | Low 16 bits of SFTS node address (the radio ID) |
| 49994 | 9993 or 65530 | Slave ID readback |
| 49995 | 9994 or 65531 | Received signal strength of last packet from the slave |
| 49996 | 9995 or 65532 | Battery voltage of the Modbus client, in millivolts |
| 49997 | 9996 or 65533 | Minutes until this slave will time out, unless new data is received |
| 49998 | 9997 or 65534 | Number of registers cached for this slave device |
| 49999 | 9998 or 65535 | Remote device type. 35 for A2_HART. |
Note: HART Register values are only reported if the HART device is detected. For example, if only HART ID 1 is connected, registers 2013-2051 will not be reported to the Gateway.
Configuration / Debug
Debug and configuration information is available via the debug port on the main board using a USB converter cable (available from SignalFire). Advanced configuration can be performed using the SignalFire Toolkit PC application.
Technical Support and Contact Information
SignalFire Telemetry
140 Locke Dr, Suite B
Marlborough, MA 01752
(978) 212-2868
support@signal-fire.com
Revision History
| Revision | Date | Changes/Updates |
|---|---|---|
| 2.4 | 8/3/16 | Updated layout. Added section on encryption. |
| 2.5 | 12/13/21 | Updated for new HART card and no DIP switches, updated register map. |
