4P642495-1A
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2022.02
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2. Modbus communication
2.1 Modbus Interface DIII settings
Communication protocol
Modbus RTU
(according to “Modicon Modbus Protocol reference guide” PI
-
MBUS-300 Rev J)
Dipswitch setting
Communication speed
9600 bps
Or 19200 bps
DS1 pin 2:Off
DS1 pin 2:On
Parity / stop bit
Even 1 stop bit
Odd 1 stop bit
None 2 stop bit
None 1 stop bit
DS1 pin 3:Off 4:Off
DS1 pin 3:Off 4: On
DS1 pin 3:On 4:Off
DS1 pin 3:On 4:On
One dedicated modbus
address setting
1..15
DS2 pin 1/2/3/4
Addr 1: Off/Off/Off/On
Addr 2: Off/Off/On/Off
…
Addr 15: On/On/On/On
Implemented function codes
0x03
Read Holding Registers (broadcast support)
0x04
Read Input Registers (broadcast support)
0x06
Preset Single Registers (No broadcast support)
0x10
Preset Multiple Registers (No broadcast support)
(remark: Holding Registers will not reflect the actual value)
(other function codes are treated as illegal function and
return an exception response)
Data types
Input Register:
Length 16 bits, Address range: 30001 - 39999
Holding Register
Length 16 bits, Address range: 40001
–
49999
(Data larger than 16 bits can be handled by assigning
continuous addresses to registers.)
Register addresses
Same address meaning for each applicable model