Schweitzer Engineering Laboratories SEL-734 - Table F.6 02 H Read Input Status Command; Table F.7 SEL-734 Meter Inputs; Table F.8 Responses to 02 H Read Input Query Errors

F.4
SEL-734 Meter Instruction Manual Date Code 20090730
Modbus RTU Communications Protocol
Modbus RTU Communications Protocol
To build the response, the meter calculates the number of bytes required to
contain the number of bits requested. If the number of bits requested is not
evenly divisible by eight, the meter adds one more byte to maintain the
balance of bits, padded by zeroes to make an even byte.
Input numbers are defined in Table F. 7.
In each row, the input numbers are assigned from the right-most input to the
left-most input (i.e., Input 1 is N and Input 8 is EN). Input addresses start at
0000 (i.e., Input 1 is located at Input Address 0000).
The meter responses to errors in the query are shown in Table F.8 .
Table F.6 02h Read Input Status Command
Bytes Field
Requests from the master must have the following format:
1 byte Slave Address
1 byte Function Code (02h)
2 bytes Address of the First Bit
2 bytes Number of Bits to Read
2 bytes CRC-16
A successful response from the slave will have the following format:
1 byte Slave Address
1 byte Function Code (02h)
1 byte Bytes of data (n)
n bytes Data
2 bytes CRC-16
Table F.7 SEL-734 Meter Inputs
Input Coil Number Input Coil Name Notes
1IN101
2IN102
3 IN401 Returns 0 if not installed
4 IN402 Returns 0 if not installed
5 IN403 Returns 0 if not installed
6 IN404 Returns 0 if not installed
Table F.8 Responses to 02h Read Input Query Errors
Error Error Code Returned
Communication
Counter Increments
Invalid bit to read Illegal Data Address (02h) Invalid Address
Invalid number of bits to read Illegal Data Value (03h) Illegal Register
Format error Illegal Data Value (03h) Bad Packet Format
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