7344 with Siemens 611U servo drive

[tymot]

I have motion experience and understand the basics. I have no NI 7344 or Simodrive 611 experience and I have been asked to get them working together within a week. The task is simple - a vertical axis, axis will drive down in velocity mode driven by a digital input to the drive. When the drive down process is complete the axis must return to the top quickly - position mode. I will datum at the top of the stroke.

Are there any examples of connections and signal interfacing between the 7344 card and the Siemens drive because getting the wiring right first time will be critical.

I would want to include, analog reference, encoder feedback, overtravel limits, home switch, axis inhibit(enable) and perhaps axis shutdown.
Any help would be
greatly appreciated.

[Jochen]

I wasn't able to find a pinout for the Simodrive 611 so I just can give you some general hints:

1. You should use a UMI-7764 or even better a UMI-7772 as a breakout box for the 7344 signals. Please refer to this link for more information:
http://sine.ni.com/apps/we/nioc.vp?cid=3310〈=US

2. Please make sure that you have connected an external power supply to your UMI. For general wiring information please refer to the UMI's user manual

3. Here are some hints for the shutdown functionality:
http://ae.natinst.com/operations/ae/public.nsf/fca7838c4500dc10862567a100753500/622529a109bad05e862569ea0060304f?OpenDocument

4. Please make sure that you have set the correct polarity for the limit switches and the inhibit output. These settings need to be aligned
with the functionality of the Simodrive

5. You need to do a servo tuning for both, the Simodrive and the 7344. First tune the Simodrive, then the 7344. I wouldn't suggest using the Autotune mechanism in MAX. Better tune the 7344 manually.
There is a very good tutorial about servo tuning on the NI developer zone:
http://zone.ni.com/devzone/conceptd.nsf/webmain/4B7775373E4AE64986256B6000691505?opendocument

Best regards,

Jochen Klier
Applications Engineering Group Leader
National Instruments Germany GmbH

[tymot]

Dear Jochen

Thanks for the reply but I cannot find the link in your answers 3 and 5,

please advise

[Jochen]

I'm sorry but I copied an NI internal link for answer 3. Here is the external link:
http://digital.ni.com/public.nsf/websearch/622529A109BAD05E862569EA0060304F?OpenDocument

You should be able to access the link from answer 5. Please tell me if you still run into problems with this link.

Best regards,

Jochen Klier

[tymot]

Hi Jochen

I have a few more details and questions.

The 7344 will control this vertical axis in both directions under normal position control and using the Siemens 611 encoder emulation signal. EXCEPT at a given position the drive down speed reference to the Siemens611 will be derived from an alternative voltage source (non digitised)whilst a machining process takes place. When this process is complete the speed reference will revert back to the 7344 which can drive the axis back to the start of the process or to the datum at the top of stroke.
I clearly need to retain the axis position to the 7344 but need to switch over without creating a major issue. How do I do this?

[Jochen]

Tymot,

this sounds a bit tricky. Looks like you have to switch the physical control signal by a relay or a switching device.

You should switch the signal while the motor is stopped and if possible without any force applied to it. As long as the encoder emulation isn't stopped the 7344 will always know where the motor is so this shouldn't be an issue.

You need to be careful when you switch back the signal and the control to the 7344. Following this sequence the switch-ver should be smooth:

1. The motor needs to be stopped and if possible no force should be applied to it.
2. Read the axis' position from the 7344.
3. Reset the position to the position you have read before. Otherwise the 7344 will try to force the axis to
move to the position when the control signal was switched. Not resetting the position could result in a hazardous jump of th axis.
4. Switch the control signal back to the 7344.

I hope this helps,

Jochen

[tymot]

Jochen

I will be switching the 7344 output off via a relay as you suggest but only whilst the axis is machining, I know that I need a "follow up" type function but I am still unclear.

[SachaE]

Hi,
I've verified this with our guys in the US.
Here's their reply

"Sounds like a setup like this would work. He would need a relay to switch sources which it sounds like he already knows. He can put a home switch at the top as a reference. He could also use a limit switch at the point at which he wants to change sources. Before changing back to the 7340 control he should do a reset position so that the servo motor is not forcing the motor to the position that it was originally (this will make up for the pulse differentiation). Other then that it should work fine. "
Hope that helps

Sacha Emery
National Instruments (UK)