InsiteIG MPA-48, Manual

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3
Function codes supported by the MPA-48
01 Read Coil Status
Description
Reads the ON/OFF status of the relays in the MPA-48 analyzer.
Query
The query message specifies the starting relay and quantity of relays to be read. Relays are
addressed starting at zero. Relays 1 – 8 are addressed as 0 – 7.
Below is an example of a request to read relays 1 – 8 from MPA-48 with slave address 1.
Field Name Example (hex)
Slave Address 01
Function 01
Starting Address Hi 00
Starting Address Lo 00
No. of Relays Hi 00
No. of Relays Lo 08
CRC --
The coil status in the response message is packed as one relay per bit of the data field. Status is
indicated as: 1 = ON; 0 = OFF. The LSB of the first data byte contains the relay addressed in the query.
The other relays follow toward the high order end of this byte.
Below is an example of a response to the previous query.
Field Name Example (hex)
Slave Address 01
Function 01
Byte Count 01
Data 05
CRC --
The status of relays 1 and 3 is ON and the status of relays 2, 4, 5, 6, 7 and 8 is OFF.