How to setup process to run when a PO line is released?

You need to create a new IPA Service (and approval flow)
Using Design Studio, add a Trigger to PO20 when a Release occurs
If you don't have Design Studio, you can add a COBOL user exit
*Note, if the PO is released it can still be processed by PO100 regardless of the flow status. If you add a Button to PO20 (via Design Studio) you can trigger the flow (with an AGS call to WFWK)and have the flow release the PO after being approved

When the PO Line is released is slightly misleading. The release occurs on the header - table is PURCHORDER.

David, unfortunately Design Studio is not yet working for us. The next best option (I guess) is to do it thru the Rich Client...can guidance be provided?...need to read up on COBOL user exit.

Also, might you know what table(s) or fields to pull the PO status such as: release, process, approve, cancel or reject? Thanks

You have to develop with Design Studio using IE 9. Rich Client won't help for a trigger.
The PO Staus should be on PURCHORDER

If you want to use something out of the box, there is a Buyer_POApprove service that gets triggered on PO Release when you have PO approvals turned on. If you don't want to use the PO functionality, you could use your process to approve it on PO18 after you do what you want.

I used the service Gen_PurchasOrd to run a flow when a Purchase Order is released.

When use Gen_PurchaseOrd service with a test process flow with a PO20 for trigger, no work unit is created. Also, that service is referencing ION EAM....not sure what means relative to a non ION flow.

Never mind----found the culprit

Can you share with us your solution? Thanks.

The solution is to reference the Gen_PurchaseOrd service definition as Jimmy had suggested and make sure the checkbox is checked for Service Is Enabled. Make sure your process flow is listed under Processes Tab for the Gen_PurchaseOrd service definition.

In PO20, under Special Actions selecting Release for a PO number will trigger a WorkUnit.

For variables, you will find the variables(148 of them) under the triggered Work Unit if you have a need to pass variables down to the process flow.