MODBUS Communication
– General
6
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TI 12J06J01-00EN-P
1.3 MODBUS communication
If the
Optical Dissolved Oxygen sensor
is used with a HOST, the following must be considered.
⚫
MODBUS response timing
The
Optical Dissolved Oxygen sensor
’s HR (HOLD Register) response to a HOST HR Read request
is within 100ms. The timing in between a response and a new request must be at least 10ms.
Figure 1.3: Timing diagram
⚫
HOLD Register renewal cycle
Process value sent in HOLD Register is configurable, initial value is 1 s.
1.4 Connection
⚫
BUS system
Wired connection:
Figure 1.4: DO71 sensor with HOST
< 100 ms
> 10 ms
HOST
HR: Hold Register
DO sensor
HR Request
HR Response
HR Request