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User manual S200 WCS
Update August 2021
10 MODBUS RTU
The S200 measuring and control device is equipped with a Modbus RTU interface.
The hardware is a RS 485 interface.
Shielding = terminal 97
A = + Terminal 96
B = - Terminal 95
10.1 Shielding
The use of shielded cables offers a high protection against electromagnetic interference,
especially against high frequencies. However, the effectiveness of the shielding is dependent
on a careful installation of the cable.
The shielding is placed near the ModBus master.
10.2 Communication parameters
Baud rate:
9600 bps
Data bits:
8
Start bits:
1
Stop bits:
1
Parity:
no
10.3 Used MODBUS functions
The following MODBUS functions are used:
• 04 (0x04) Read Input Registers – reading of max. 40 register
• 06 (0x06) Write Single Register – writing 1 register
10.4 List of Modbus re gister S200
Register
Description
Unit
Value range
Position
decimal
point
R/W
0
Measuring value pH
pH
-
200…1600
xx.xx
R
1
Measuring value ORP
mV
-1500...+1500
xxxx
R
2
Measuring POT - measurement
Mg/L
0... 500
xxx.x
R
3
Measuring value temperature
°C
-
3000…14000
xxx.xx
R
9
Measuring flow measuring water
L/h
0 - 120
xxx
R
10
Measuring active chlorine
mg/L
0... 500
x.xx
R
Note:
To read register 0 (measured value pH), the MODBUS register 30001 must be
selected. The MODBUS address is shifted by +1 at a time.
