EPS IPES-IR3, Operating Manual

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820-0003 IPES IR3 Flame Detector
Operating Manual
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Appendix B: IPES Digital Communications Protocol
IPES Commands In addition to supporting analog signals (current loop and relays), IPES ‐ IR3 flame detectors are also capable
of digital communications with remote consoles. IPES ‐ IR3 detectors use a standard RS ‐ 485 interface with a
Modbus RTU protocol layer defining the transactions between the IPES ‐ IR3 and the console. Refer to the
document “MODBUS APPLICATION PROTOCOL SPECIFICATION v1.1bx” available online at
www.modbus.org for complete details of the Modbus protocol.
Setting Address/ Baud
Rate Command The factory default Modbus address for the IPES ‐ IR3 is 247. The factory default baud rate for each
detector is 9600.
The following 8 ‐ byte Modbus command must be sent to the IPES ‐ IR3 in order for the Modbus
address and baud rate to be changed:
Set address/baud rate command
Byte Description
0 Current Modbus address (247 if IPES‐IR3 set to factory default)
1 6 (Modbus function code for writing to the device)
2 0
3 0
4 New Modbus address (must be in the range 1 to 247)
5 New baud rate (must be one of the following values):
1 – 1200 baud
2 – 2400 baud
4 – 4800 baud
8 – 9600 baud
16 – 19200 baud
6 Low byte of 16‐bit CRC
7 High byte of 16‐bit CRC
The IPES ‐ IR3 will respond to the host by transmitting an identical packet to the host at the original baud
that was used to receive the command. After the response has been transmitted, the IPES ‐ IR3 will change
its Modbus address and baud rate to the ones specified in the command. At that point, the remote console
must change its baud rate in order to communicate further with the detector. The new Modbus address
and baud rate are stored in non
‐ volatile memory and these parameters will be retained through power
cycles.
The Modbus address and baud rate are stored in non‐volatile
memory with a write endurance of 10000 erase‐write cycles.
Repeated transmission of the set address/baud rate command to the
IPES‐IR3 detector can potentially degrad e the memory beyond its
ability to retain the data being written to it. The address and baud
rate should be changed only when necessary to connect the IPE
S‐IR3
detector to a remote console.