Deployment
Wieland Electric GmbH | BA001269 | 09/2021 (Rev. A)
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6.9
Modbus function codes
Naming convention
Modbus has some naming conventions:
•
Modbus differentiates between bit and word access; Bits = 'Coils' and Words = 'Register'.
•
Bit inputs are referred to as 'Input-Status' and bit outputs as 'Coil Status'.
•
Word inputs are referred to as 'Input-Register' and word outputs as 'Holding Register'.
Range definitions
Normally the access with Modbus happens by means of the ranges 0x, 1x, 3x and 4x.
0x and 1x gives you access to digital bit areas and 3x and 4x to analog word areas.
For the
ricos
FLEX BC MODBUS is not differentiating digital and analog data, the following assign-
ment is valid:
•
0x – Bit area for master output
Access via function code 01h, 05h, 0Fh
•
1x – Bit area for master input
Access via function code 02h
•
3x – Word area for master input
Access via function code 04h, 17h
•
4x – Word area for master output
Access via function code 03h, 06h, 10h, 16h, 17h
