ETC is requesting all devices by queue in the loop

 and request-response to each device takes some time period.

Some device or segment in the loop might delay requests to all devices in the  

queue.


Check next:


1) Are there other devices in the loop where receiving response is delayed.

Are they located in same area?


2) Check response time for each separate device in PAS.

    one of several problematic devices might delay requesting all other devices in the loop.


3) Check correctness of RS485 network installation.


Here are some requirements:

  a) Should be used twisted pair cable. Shielded is recommended.

  b) Communication cable must be installed separately from power supply of current 

     measuring cables.

 c) All devices must be connected by a chain one after another. 

     Star connection in not allowed.

 d) Each segment of shield cable must connected only from one side to device port.

 e) Should be installed termination resistors from both sided of the loop.

     See illustration for example below.

    

image




General recommendation :In order to reduce total response time rise baud rate of all slave devices and the master port.