Produce&consume tags or using MSG instruction

[ziyaddin2015]

Hi all,
We have a packaging machine in our plant that has a cartoner and the casepcker. If caspacker goes down for 5-10minutes this shuts of cartoner as well which then requires operator intervention. What i would like to do is keep it somehow in standy or pause mode and restart whenever case packers resume production. Is this can be fixed with consume &produce tags or msg instruction between two controllers? What would be the best solution? Thank you

 

[OkiePC]

The Produced/Consumed tag requires less code to set up, but does require a stoppage of each PLC involved to download the programs to implement. It will also produce an I/O error LED on the consumer CPU when the tag it is trying to read cannot be accessed. This method also can be set up to provide the status of the Producer PLC Run Mode status although this feature may not be available with older revisions.

The MSG instruction can be implement online without halting the process. It will require more care and thought to ensure that you detect when the remote CPU is not only available but in run mode.

I like using Produced/Consumed tags because it is cleaner and I don't have to create the heartbeat check to prove the remote PLC is not faulted. If I must not stop the process or they have folks who will frown at the I/O error LED being lit, I will use the MSG method.

 

[Gadelric]

Both would work, I prefer produce/consume but this requires downloading the program, message instructions can be put in as a live edit.

I have a couple of questions though.

1.) Do these machines not already talk to each other?
2.) How does machine 1 know machine 2 is down and vise versa? idle time out?

Although I cant guarantee anything, I would presume that these being two different machines, that work together, there would be some talking back and forth already.

 

[alive15]

Hey Ziyaddin,

What logic causes your cartoner to go down right now? Just eliminate logic that turns this machine off, and that should solve the problem, no?

Like Gadelric said, some form of communication should already be there. My guess is the cartoner has a timer and it knows how long the casepacker has been down for. Eliminate this timer, and you should be good to go?

 

[janner_10]

Check there isn't a simple prox that sits between the two that shuts down the cartoner if the build back passes a certain point. Simply move this sensor back so it allows more accumulation before the cartoner shuts down.

 

[OkiePC]

Yes, I blew right past the description of the problem... When I worked with this type of machinery, there was usually a photocell on a conveyor between the carton erector and the packing machine. If the cartons backed up and kept the photocell blocked for a certain number of seconds, the carton erector would pause (not shut down). Our carton erectors were simple machines with no PLCs, but even so, there should be a way through wiring or programming of the carton erector to change it so that it can pause and resume rather than stop and require a person to restart it. If you make such a change, be sure to consider all safety ramifications and ensure the changes are communicated to all affected operators ... Once modified, signage like "THIS MACHINE MAY START AUTOMATICALLY!" might be required.