2
Function codes supported by the Model 2000
01 Read Coil Status
Description
Reads the ON/OFF status of the relays in the Model 2000 analyzer.
Query
The query message specifies the starting relay and quantity of relays to be read. Relays are
addressed starting at zero. Relays 1 – 4 are addressed as 0 – 3.
Below is an example of a request to read relays 1 – 4 from Model 2000 with slave address 1.
Field Name Example
Slave Address 01
Function 01
Starting Address Hi 00
Starting Address Lo 00
No. of Relays Hi 00
No. of Relays Lo 04
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
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 and 4 is OFF.
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