Communication via Modbus TCP
6.7 Communication procedure
Communication
180 Function Manual, 12/2018, 6SL3097-5BD00-0BP0
6.7 Communication procedure
Logical error
If the device detects a logical error within a request, it responds to the controller with an
"exception response". In the response, the device sets the highest bit in the function code to
1. If the device receives, for example, an unsupported function code from the controller, the
device responds with an "exception response" with code 01 (illegal function code).
Table 6- 18 Overview of exception codes
01 Illegal function code An unknown (unsupported) function code was sent to the
An invalid address was requested.
An invalid data value was detected.
04 Server failure The device terminated during processing.
Process data monitoring time (setpoint timeout)
The "Setpoint timeout" only applies for access to process data (40100 ... 40109, 40110 ...
40119). The "Setpoint timeout" is not generated for parameter data (40300 … 40522).
Fieldbus interface:
In parameter p2040 you define the time for cyclic data exchange for process data.
Setting range 0 - 2000 s.
The time depends on the amount of data to be transferred and the control.
"Setpoint timeout" (F01910) is issued by the Modbus if p2040 is set to a value > 0 ms and no
process data is requested within this time period.
COMM BOARD:
In parameter p8840 you define the time for cyclic process data exchange.
Setting range 0 - 2000 s.
The time depends on the amount of data to be transferred and the control.
"Setpoint timeout" (F08501) is issued by the Modbus if p8840 is set to a value > 0 ms and no
process data is requested within this time period.
To Next Page
Loading...
