Specifications

D3.6 Communication error

During PCS - programmable controller communication, the PCS operates as master

and the programmable controller as slave. Thus, it is the task of the PCS to set up

and monitor communication. Thereby, the correct communication is monitored

between the programmable controller and the PCS. The following error message

is provided for this purpose:

======== COMMUNICATION ERROR ============

TIMEOUT

In both, in the PCS and in the programmable controller there is a time monitoring

function for the serial data exchange and sync. word processing. In the PCS, the

time-out time totals 4 seconds as default value. After that an error message is

displayed in the PCS and the error LED flashes. The PCS tries again to establish

the communication in the background. If this is successful and word 3 is processed,

then the above shown error message is erased. Example: Interruption of the adapter

cables.

The data interchange is performed in data blocks and each block is examined for

length, content and block check. If a fault is discovered, then the block is requested

once more. With more repetitions in a sequence, the communication is interrupted

and the above shown error message appears.

======== COMMUNICATION ERROR ============

Timeout programmable controller

The status of the programmable controller is scanned during establishing the

communication. Thus, the PCS can ascertain whether the programmable controller

is in RUN mode. If the programmable controller in the STOP mode then the above-

mentioned message appears. If the programmable controller is switched into RUN

mode then the message is erased and the communication is resumed.

Communication