Re: Support for Gamma Vacuum MPCq ion pump controller over Ethernet

[LiangChih Chiang via Tech-talk <tech-talk at aps.anl.gov>]

>We have been facing an issue with the Ethernet interface where the device does not reply with the appropriate response, 

>for example you request pressure and it returns voltage. 

I encountered the same issue.

>Assuming the latest firmware is installed, we used to reboot the IOC to fix it, but if you include asynRecord.db and disconnect the asyn port 

>it will connect again and will work. 

>My initial guess for the root cause is requesting multiple commands at the same time over time, 

>that’s why I made the database processing sequential using a chain of FLNKs, this reduced the issue very much.

My obversation is that sometimes the reply-processing code A may receive the reply from command B.

And that may cause memory access violation.

On Sun, Jan 25, 2026 at 2:28 PM Abdalla Ahmad via Tech-talk <tech-talk at aps.anl.gov> wrote:

Hi Mark

 

We are controlling the QPC model over Ethernet with Stream device. A quick look at MPC user manual shows a very similar Ethernet interface to the QPC. I attached the protocol file, a sample database and a working POC of the Modbus interface. However, from our experience I have some comments:

• We have been facing an issue with the Ethernet interface where the device does not reply with the appropriate response, for example you request pressure and it returns voltage. Assuming the latest firmware is installed, we used to reboot the IOC to fix it, but if you include asynRecord.db and disconnect the asyn port it will connect again and will work. My initial guess for the root cause is requesting multiple commands at the same time over time, that’s why I made the database processing sequential using a chain of FLNKs, this reduced the issue very much.
• Though not test thoroughly, I think the Modbus interface is a bit more stable and faster than the ethernet, I tested both on the same controller in the same IOC, I was able to see updates on the Modbus port a bit faster than the Ethernet.

 

Best Regards,

Abdalla Al-Dalleh

Control Engineer

SESAME

 

From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Mark Rivers via Tech-talk
Sent: Saturday, January 24, 2026 1:22 AM
To: EPICS Tech Talk <tech-talk at aps.anl.gov>
Subject: Support for Gamma Vacuum MPCq ion pump controller over Ethernet

 

Folks,

 

I have been using this old C device support to talk to Gamma Vacuum MPC ion pump controllers.

 

https://github.com/epics-modules/ip/blob/master/ipApp/src/devMPC.c

https://github.com/epics-modules/ip/blob/master/ipApp/Db/MPC.db

 

This only talks via RS-232, but many of their newer modules support Ethernet.  The Ethernet message format is somewhat different.  Has anyone written StreamDevice support for the Ethernet protocol?

 

Thanks

Mark