Re: MAXnet Alarm State Under High Motor Command Load

["Peterson, Kevin M. via Tech-talk" <tech-talk at aps.anl.gov>]

Jiajun,

Are there any MAXnet communication errors on the IOC's shell when the bluesky/ophyd errors occur?

Kevin


________________________________________
From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Jiajun Tian via Tech-talk <tech-talk at aps.anl.gov>
Sent: Wednesday, January 28, 2026 10:32 AM
To: tech-talk at aps.anl.gov
Subject: MAXnet Alarm State Under High Motor Command Load

Hi All,

We are using an OMS MAXnet motor controller via an EPICS IOC, with motion driven by Bluesky plans (Ophyd). Under a high rate of consecutive motor move commands, the motor PVs enter an EPICS alarm state after several moves. When this happens, Ophyd reports a failed MoveStatus, and the Bluesky RunEngine aborts.

The MAXnet is primarily connected via Ethernet. We have also observed similar behavior when using a serial connection, where the issue occurs more frequently.

Has anyone experienced similar MAXnet issues with EPICS, or can advise on relevant settings or configuration considerations?

Related error observed in Bluesky/Ophyd:
ERROR:ophyd.objects: Motion failed: sx is in an alarm state status=AlarmStatus.STATE severity=AlarmSeverity.MAJOR

Thanks in advance,
Jiajun




Jiajun Tian, Ph.D.

Postdoctoral Researcher
NSF’s ChemMatCARS, Pritzker School of Molecular Engineering
University of Chicago
9700 S Cass Ave Bldg 434D
Lemont, IL-60439
United States