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INM MTL SUM5 Rev 7
DRAFT - 09 June 2021 DRAFT - 09 June 2021
Typical Example of Message Format
To read all contact status data on a 32 way SmartAlarm the following message format has to be
repeated 4 times, once for each alarm card node address.
RTU
ADDRESS FUNCTION REGISTER
ADDRESS
No Of
REGISTERS
ERROR CHECK
01 01 00 01 00 08 6C 0C
Example shows message for rst card, Comms address offset 0.
33.3 Read Status – Function 03 – Read Request – Master
Register Address
This is used to address the “start” channel to be read, typically the rst channel “channel 1” contact
status on alarm card would be register address 40001
To read the contact status registers use address range 40001- 40008
To read the alarm status registers use address range 40011- 40018
To read the disable status registers use address range 40021- 40028
Number of Registers
This represents the number of registers (Channels) the master wishes to read. The range is 1- 8.
33.4 Read Status – Function 03 – Read Response - Slave
Byte Count
This represents the number of bytes sent
Data
Data returned depends on register address originally specied by the master.
Register address 40001 - 40008 returns Contact status data
0 = Normal
1 = Abnormal