INM 725B Rev 21
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13 .4 .19 Read Status – Function 03 – Request
Register Address
This is used to address the “start” register to be read from the slave device
Number of Registers
This represents the number of registers to be read from the salve device this can be up to 125
register at once.
13 .4 .20 Read Status – Function 03 – Response
Byte Count
This represents the number of bytes sent
Data
The data read from the salve device needs to be a valid value to operate the input.
If Channel set to Normally Open
Value AND’d with register mask not equal to register mask – Input Normal
Value AND’d with register mask equal to register mask – Input Abnormal
If Channel set to Normally Closed
Value AND’d with register mask not equal to register mask – Input Abnormal
Value AND’d with register mask equal to register mask – Input Normal
Typical Request Message Format Example
To read 28 registers on slave with node 9 the user would use the following message format
RTU
ADDRESS
FUNCTION
REGISTER ADDRESS
No. of REGISTERS
ERROR CHECK
09
03
00 00
00 1C
45 4B
ASCII
:
ADDRESS
FUNCTION
REGISTER
ADDRESS
No. of
Registers
ERROR
CHECK
CR
LF
3A
30 39
30 33
30 30 30 30
30 30 31 43
44 38
0D
0A
