Empty stack error Code: -60

I recently got back on a long term side project of resurrecting our old windtunnel. Between the last time i worked on it and now we have upgraded all the PCs throughout the company from Windows XP to 7. I downloaded and installed pac project 9.4 and opened the project. I had a two issues up front. First, I had to make a control engine on the new pc. Second, I didn’t have the network drives mapped using the same drive letters. This caused an issue with the file locations of files used to load tables after strategy download. These problems have been fixed.

When trying to enter debug mode, it states that the control engine’s memory has been cleared, and askes to continue downloading strategy. After clicking yes, the following message pops up after the download begins.

Empty stack error. Control engine attempted to preform an operation that expected data on the control engine stack.
Code: -60

I am coming up empty handed trying to look this error up. any help?

This seems to only be an issue with 9.4 as I just downloaded 9.3 off the FTP site and ran from a backup version and it loads and runs fine. :confused:

Hello drumz2129,

If you have any PIDs in your strategy, you might be running into [U][B]this 9.4b bug[/B][/U] (which causes the output in your PIDs to get messed up). Those funky PIDs can cause all kinds of weird things happen, especially during a download. The software developers are working on a fix.

If PAC Control 9.3 is okay (you don’t need any of the new modules or features we added in 9.4), I’d stick with that for now.


I got this error which prevents me from downloading the new program in the controller. I got it this week but I’ve been working on this project for months. If I try to step back to v9.3, I’ll have to go to a very early version of my code. Is there a solution for this? The VFD_PID mentioned in the bottom used to be a Mistic I/O PID that I have erased. I’ve tried to click on the object tree, CTRL-R to rebuild but the program just crashes.

Do you have ANY remaining PIDs in that strategy?

We to have a beta which addresses this. I’d recommend you contact our support team (support@opto22.com) and send them the archive of your strategy so they can:

  1. Confirm the beta will fix your strategy
  2. Give you instructions for getting the Beta if it does
  3. Find other options for you, if available


Yes, they are new PIDs.