CLX block transfer limitation

Hello

I am using a 1756-DHRIO to scan a analogs cards in the plc-5 and BTR and BTW instruction to read and config that cards.
I have 17 analog cards and happens 1 normaly is not working. When I put in remote and again in run normaly the card is not working starts to work and another not working.

Anybody knows what is the reason for that?

Nuno Carvalho

Because the limit to cached BTR or BTW instructions in the ControlLogix CPU is 16.

You will need to un-cache at least some of the connections. There are Knowledgebase documents about this technique that you can look up.

Hi Eddie Willers

It's possible you give a explination more in detail or give me a example.

Nuno Carvalho

In addition to what Eddie referenced, the DHRIO to 1771-ASB can only handle one BT at a time ... you will need to put in a message management logic to only trigger one BT(R/W) at a time.

RA has a tech note on this ... it also has an example of the message manager logic.

Anyone have the possibility to send a techicalnote from rockwell 30621?

thank you