Preset Single Register - Function Code 06; Preset Single Register Query; Preset Single Register Response; Loopback Test - Function Code 08 - ABB C1300 User Manual Supplement

C1300
Advanced Circular Chart Recorder
5.4 Preset Single Register – Function Code 06

5.4.1 Preset Single Register Query

The preset single register allows the user to modify the contents of a holding register.
Note. Function codes 5, 6 and 16 are the only messages that are recognized as valid for broadcast.
Example – a preset single register request to write the value 500 to holding register address 121 (alarm trip A1) in slave 01 is shown
below.
Note. To write to a register, the register's offset address must be used, e.g. to write to register 121, the offset address 120(78H)
is transmitted.
Address Function
01 06

5.4.2 Preset Single Register Response

The normal response to a preset single register request is to retransmit the query message after the register has been altered.
Example:
Address Function
01 06
5.5 Loopback Test – Function Code 08

5.5.1 Loopback Test Query

The purpose of the loopback test is to test the Modbus system, it does not affect the content of the controller. Variations in the
response may indicate faults in the Modbus system. The information field contains 2 bytes for the designation of the diagnostic code
followed by 2 bytes to designate the action to be taken.
Example:
Address Function
01 08
*These are considered to be the information fields for diagnostic mode.

5.5.2 Loopback Test Response

The response always echoes the query, only diagnostic code 0 (bytes 3 and 4) can be used.
Example:
Address Function
01 08
*These are considered to be the information fields for diagnostic mode.
IM/C1300–MOD Rev. C
Register Offset
High Low
00 78
Register Offset
High Low
00 78
Data Diagnostic Code
High Low
00 00
Data Diagnostic Code
High Low
00 00
Data Value
High Low
01 F4
Data Value
High Low
01 F4
Data* Data*
A5 37
Data* Data*
A5 37
5 Modbus Functions
Error Check Field (CRC-16)
09 C4
Error Check Field (CRC-16)
09 C4
Error Check Field (CRC-16)
DA 8D
Error Check Field (CRC-16)
DA 8D
11