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V: 1.10 Revised: January 2020
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Chapter 9: Description of Modbus-TCP Protocol
1) Read Status of Relay (Function code 01)
Function Code 1
This function code is used to read the relay output status in the Acuvim II series meter.
1=On 0=Off
There are 8 relay outputs in the Acuvim II series meter and they start at address 0000H.
The following query is to read 2 relay output status of the Acuvim II series address 1.
Query
Transaction
identifier hi
Transaction
identifier lo
Protocol
identifier hi
Protocol
identifier lo
Length hi
Length lo
Unit
identifier
00H
00H
00H
00H
00H
06H
01H
Fun
Data start
register hi
Data start
register lo
Data # of
registers hi
Data # of
registers lo
01H
00H
00H
00H
02H
Response
The Acuvim II series meter responds back with the MBAP header, function code, quantity
of data bytes and the data.
An example of response to read the status of the first 2 relay outputs starting at 0000H is
shown below. The status of relay output 1 and 2 is corresponds to the last 2 bits of data.
Relay 1: bit0 Relay 2: bit1
Transaction
identifier hi
Transaction
identifier lo
Protocol
identifier hi
Protocol
identifier lo
Length hi
Length lo
Unit
identifier
00H
00H
00H
00H
00H
04H
01H
Fun
Byte count
Data
01H
01H
02H