It looks like you are using an UNO and a Mega.
Are you using serial communication, and is your "AND" problem related to I/O from the Arduino's?

If yes...
Are /dev/ttyACM0 and /dev/ttyACM1 always pointing to the right Arduino (udev rules)?
Are you sure you have no stall issues in the Arduino's communication?

/Marc

Hi.

I have nothing advanced in my CAritm blocks. No arrays or pointers.
I find this very strange as similar code works fine in the same program.

Maye I will just remove all my plc programs and start over.

I would like to upgrade to the lates version of Proview, but there is no 386 version for Ubuntu. Will that be available?

Regards,
Trygve

Hi Mark,

At the moment I don't have the hardware connected, and the code is working for the two valves shown at the top of the code. As far as I can see it's implemented identical for the valves the is working and for the ones that don't work.

When the hardware is connected all the valves can be operated.

Regards,
Trygve

What microprocessor are you using and how much RAM? These days, there
is a very high probability you can run 64-bit LUBUNTU or UBUNTU and 64-
bit Proview. Most computers are capable, even those discarded long ago.
If possible, try 64-bit O/S and 64-bit Proview.

en.wikipedia.org/wiki/List_of_Intel_microprocessors

Claes is always right regarding all things Proview. With only one plc
thread, running multiple plcgrms sequentially should not create any
timing issues (as in your case). Claes, thanks for clarifying.

Based on your label, it appears you may be running 100 mSec plc thread?
Have you tried slowing down to say 1000 mSec to see if that makes a
difference? Also, which plcpgm has the non-functioning AND block?

Also, double check all of your block connections in the PLCPGM with the non-functioning AND block. Be double sure to use proper type connectors (forward (solid) versus backward (dashed)). I've seen PLC programs not work correctly due to misconfigured "schedule loops" caused by incorrectly using a forward connector to loop backwards. No syntax or compile errors were given.

/Ron