Watlow CLS200, MLS300 and CAS200 User Manual download pdf (Page 32)

26 Communications Speciﬁcation

Chapter 2: Modbus-RTU Protocol

This process is repeated until eight shifts have been performed. After the

last shift, the next 8-bit byte is exclusive ORed with the register’s

current value, and the process repeats 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 CLS

controllers. Codes are listed in decimal.

x01 Read Coil Status

• Reads the On/Off status of discrete outputs (registers 00001 to

09999, the coils) in the slave. Broadcast is not supported.

x02 Read Input Status

• Reads the On/Off status of discrete inputs (registers 10001 to 19999)

in the slave. Broadcast is not supported.

x03 Read Holding Registers

• Reads the binary contents of holding registers (registers 40001 to

49999) in the slave. Broadcast is not supported.

x04 Read Input Registers

• Reads the binary contents of input registers (registers 30001 to

39999) in the slave. Broadcast is not supported.

x05 Force Single Coil

• Forces a single coil (registers 00001 to 09999, the coils) to either On

or Off. When broadcast, the function forces the same coil reference

in all attached slaves.

Code

in Hex

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

0F Force Multiple Coils

10 Preset Multiple Registers

1 2 ... 27 28 29 30 31 32 33 34 35 36 37 ... 91 92

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Watlow CLS200, MLS300 and CAS200 User Manual Page 32