If you enable the system memory and clock bytes in the hardware configuration of your PLC, you get an automated clock that you can use as a trigger to the MB_CLIENT block's REQ input.

Just put a P_TRIG or -|p|- after the clock pulser.

If you need it faster, you can send as soon as your last one sent successfully (or had an error).

Sounds like you are doing well so far.  Good job. 

U_d50189cc-23c0-40c4-a605-6cb0642dfd90

I am new to PLC, so please go soft on me.

... what is in the read register 1.

Also is it possible to set the REQ ID1 and REQ ID 4 to an high so that the MB_CLIENT is automatically and continuous.

Thanks

EDIT: I managed to get the Input output bits to move to an array of word using the move block..

I would still like to get MB_CLIENT function to read and write automatically without toggling the REQ_ID1 or REQ_ID4 button.

Take a look at the F1-Help for the MB_CLIENT to see what the REQ signal does and requires.

If I recall correctly, it requires a leading edge transition to request anything to happen.  Always ON is one leading edge, so you get exactly one transaction.

You are only flooding the network if you use a FAST clock pulser.  If you use one second or longer, that is very slow on a network.

If you attempt to go faster than you can, the reliance on looking at the done bit first to re-trigger keeps you from resending too fast.

You can always delay a short amount of time after the DONE/ERROR to resend.  One of the things I do is after 3 failures, I retry every 10 seconds until I reacquire a DONE, then go back to normal sending.

If you see repeated failures that create a retry - retry - retry - delay - done - done - done - retry or something where it keeps retrying, you have a physical network issue to resolve. 

U_d50189cc-23c0-40c4-a605-6cb0642dfd90

Thanks Huggy for the reply.

I managed to get the system memory byte enabled. Can I just use the "Always True" bit to trigger the Req in MB client; instead of using the clock memory. Obviously I am flooding the network with requests; if i do that.

How effectively do i use the clock memory bit if the MB_CLIENT time out is set to default.

If I have two MB_CLIENT functions (one for read register and other for write register)   do I use the same bit to trigger both. Or do i use p trigger for one and N trigger for another together with the clock memory bit.

Sorry if i questions looks too basic..

Thanks again for the help

What you want to do is set up a sequencer that creates your MB_CLIENT REQ triggers, fault detection, retry/fail/fault, and init logic.  (Just my opinion).

You can use the plc agnostic approach and use a couple of simple integers, some compares and move blocks to step through your sequencers.

NOTE: YOU CANNOT COPY/PASTE THIS CODE AND EXPECT IT TO DO ANYTHING!

IF FirstScan THEN

  #SEQ_NEXT := 100;

  #SEQ := 100;

END_IF;

IF #SEQ == 100 THEN   // INIT

  CALL YOUR FB TO INIT CLIENT #1 DBs, etc.

  CALL YOUR FB TO INIT CLIENT #2 DBs, etc.

  #SEQ_NEXT := 200;

END_IF;

IF #SEQ == 200 THEN // SET UP TO RUN

  #MB1_TRIGGER := true;

  #MB2_TRIGGER := false;

END_IF;

IF #SEQ == 210 THEN // SEND TO CLIENT #1

  [add MB_CLIENT setup here with #MB1_TRIGGER at REQ input, assume FB DB Name is:

     MB1_CLIENT_CALL_FB ]

  #MB1_TRIGGER := false;

  IF MB1_CLIENT_CALL_FB.DONE OR MB1_CLIENT_CALL_FB.ERROR THEN

    #MB2_TRIGGER := true;

    #SEQ_NEXT := 220;

  END_IF;

END_IF;

IF #SEQ == 220 THEN // SEND TO CLIENT #2

  [add MB_CLIENT setup here with #MB2_TRIGGER at REQ input, assume FB DB Name is:

  MB2_CLIENT_CALL_FB ]

  #MB2_TRIGGER := false;

  IF MB2_CLIENT_CALL_FB.DONE OR MB2_CLIENT_CALL_FB.ERROR THEN

    #MB1_TRIGGER := true;

    #SEQ_NEXT := 210;  // START OVER FOR CLIENT #1

  END_IF;

END_IF;

#SEQ := #SEQ_NEXT;  // LAST STEP IN FB (prevent order of solve problems)

This is simple sequencing logic without any retry/fault handing.  It just polls each device one after the other forever.

U_d50189cc-23c0-40c4-a605-6cb0642dfd90

How does the system memory and clock memory work.

At the moment I have enabled it in the device configuration. But I cant see it toggling at all. Even the Always On is 0.

Do not know what mistake Iam making. I am using TIA V13.

EDIT:  seems like i was only downloading software changes. Once I downloaded the hardware changes the clock memory started to work.

However, I am still struggling to get the sequencing between the two MB_client to work. Is there any examples somebody can point to or help me with.