Modbus Slave - Function Codes - YASKAWA CP 341 Manual

VIPA System 300S

6.4.8 Modbus Slave - Function codes

Naming convention
Modbus Function codes
FC Function
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 Loop back test
15 Force multiple coils
16 Preset multiple registers
HB130 | CP | 341-1CH01 | en | 18-40
Modbus has some naming conventions:
n Modbus differentiates between bit and word access; Bits = "Coils" and Words = "Reg-
ister".
n Bit inputs are referred to as "Input-Status" and Bit outputs as "Coil-Status".
n Word inputs are referred to as "Input-Register" and Word outputs as "Holding-Reg-
ister".
The following function codes are supported by the driver:
– The Modbus slave driver supports a maximum data block length of
512 data words in all the function codes, which access the DBs in the
CPU (FC 03, 04, 06, 16).
– One DB may be accessed by one message.
– Otherwise you get an error message.
Action in the PLC
read in bits
read in bits
read in bits (16bit grid)
read in bits (16bit grid)
read in bits
read in bits
read in words
read in words
write in bits
write in bits
write in words
-
write in bits (1...2040bits)
write in bits (1...2040bits)
write in words (1...127 Register)
Communication protocols
Modbus > Modbus Slave - Function codes
Memory bits M
Outputs Q
Timer T
Counter C
Memory bits M
Inputs I
Data block DB
Data block DB
Memory bits M
Outputs Q
Data block DB
-
Memory bits M
Outputs Q
Data block DB
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