Beckhoff

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Beckhoff motor controllers are the most complex in use at ISIS and will be the standard going forward. A Beckhoff controller is basically a generic PLC that includes a number of useful functions out of the box for running motors. The generality of a beckhoff means that it will most likely be used in the future for measuring and controlling other hardware outside of motion. A more detailed presentation has been given about Beckhoffs in a Code Chat entitled Layers, Onions and Ogres.

Documentation

• Axis and Controller Commissioning Guide document describing setting up a controller and TwinCAT solution for a new system and configuring real and virtual axes within TwinCAT environment.

Code on the controller

Unlike most other devices (except the Galil) the computing group has some oversight over the PLC code written on the controller. It has been agreed that this code will mostly be written by IDD, with oversight from computing to guide good programming practices, assist in debugging etc. The ISIS first version of this code is stored here however this is now not used and going forward the code is written in collaboration with the ESS and stored here.

Testing

See Beckhoff testing

Commissioning a new Beckhoff on a beamline

see Beckhoff Commissioning

IOC

Beckhoff config area

The config area contains a directory used for storing .tpy files for use with tcIoc. On an instrument it should look like this: \instrument\settings\config\<instname>\configurations\twincat\. The TC IOC will search in this directory using the given TPY_FILE macro. The generated DB file also gets created in this directory by tcIoc.

Updating

Some discussion has been had on how we handle updates to the Beckhoff PLC code and tcIoc etc. this is documented here

Troubleshooting

As we don't really handle any logic minus the motor record aliasing, there isn't much to go wrong (in theory) - sometimes for numerous reasons such as motion logic changing etc. the .tpy file that maps over memory addresses to human readable names can go out of date.

"TPY file needs updating"

If nothing whatsoever is working, moves aren't sending and enabling/disabling is not working, an outdated .tpy file could be the cause.

To remedy this:

1. Stop the TC IOC from IBEX.
2. Obtain a valid/up to date .tpy file, either sent from the motion team or from the controller (usually under C:\TwinCAT\3.1\Boot\Plc\, named port_852.tpy, you can remote desktop in using the PLC's IP address and use a file explorer to copy it from its Windows environment)
3. Place above .tpy file in C:\Instrument\Settings\Config\NDX<instname>\configurations\twincat\ - it will need to be called whatever it was before or whatever it was in the config (it's passed in via a macro) - it's usually called tc_project_app.tpy
4. Start the TC IOC again from IBEX. This should re-generate the .db file in the above directory and you should now have working communication. The table of motors may take a while to update so to check if things are working it may be easiest to use the Beckhoff Engineering device screen. If this does not exist on an instrument, create it.

Unable to set limits and multiple errors.

Safety systems such as light curtains or bump strips will throw the controller into error (and usually disable all axes) and prevent limits being set, as opposed to just stopping movement like on a Galil. The green reset button on each beamline should clear the error and re-enable.

Motor not responding to set points, no errors in log, "controller error" message

In this case, navigating to the TwinCAT Beckhoff Controller OPI, selecting the troublesome axis, then pressing "load" then "reset" cleared the issue.

currentTime::getCurrentTime(): time discontinuity detected

This is a weird error that seems to occur sometimes when running a Beckhoff simulator. To stop it you need to do run unsettick.bat script in tcioc\master and reboot. NB this should never happen on an instrument machine as they do not run simulated Beckhoffs.

Twincat Beckhoff Engineering View

Error: 19250

To resolve, a physical restart was necessary - Contact Electrical and Electronic User Support Group to resolve Once a physical restart has taken place, load each axis and reload to check the error status has returned back to 0.

Error: 17510 or 19209

Occur during physical restart, and may remaining if physical restart was unsuccessful. Once a successful physical restart has taken place, they should go away. - Contact Electrical and Electronic User Support Group to resolve this

Error: 18000

Axes may not move at all when under 18000 error. To resolve, reset using Beckhoff Engineering View and / or perform homing routine.