
Appendix A: Modbus Protocol CPC400 Series User’s Guide
190 Watlow Anafaze Doc. 0600-2900-2000
ORed with the register’s current value, and the process re-
peats for eight more shifts as described above. The final
contents of the register, after all the bytes of the message
have been applied, is the CRC value.
Function Codes
The listing below shows the function codes supported by
the CPC400 controllers. Codes are listed in decimal.
Table A.1 Function Codes
Read Coil Status 01
Reads the on/off status of discrete outputs (0X references,
coils) in the slave. Broadcast is not supported.
Read Input Status 02
Reads the on/off status of discrete inputs (1X references) in
the slave. Broadcast is not supported.
Read Holding Registers 03
Reads the binary contents of holding registers (4X referenc-
es) in the slave. Broadcast is not supported.
Read Input Registers 04
Reads the binary contents of input registers (3X references)
in the slave. Broadcast is not supported.
Code
Decimal
Name
01 Read Coil Status
02 Read Input Status
03 Read Holding Registers
04 Read Input Registers
05 Force Single Coil
06 Preset Single Register
08 Diagnostics
15 Force Multiple Coils
16 Preset Multiple Registers
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