How can I connect Gemini GT-L5 to UMI-7764

[mprover1]

Ive got a Gemini GT-L5, a UMI-7764 connected to a PCI-7344 card. I wanted to know if anyone knew how to connect a GT-L5 Stepper Drive to the UMI-7764. The gemini GT-L5 Pinouts are below,

http://www.cmotor.com/literature/pdf/pg073_gemGTGT6_led.pdf

and the UMI-7764 pinouts are
http://www.ni.com/pdf/products/us/4mo640-641.pdf


I aprecaite any help
Josh

[mhaag]

Josh,

I would recommend taking a look at the following discussion forum post where a user discusses connecting a UMI 7764 to a Gemini GV drive. While this may not match exactly, it contains some good information on the key connections that need to be made, such as the encoders (assuming you are using a closed loop stepper) and other inputs:

http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RNAME=ViewQuestion&HOID=506500000008000000DD490000&ECategory=Motion

Also, if you have not seen it already, you can read through the user guide for the 7764 to learn a little bit more about the connections

UMI 7764 User Guide:
http://digital.ni.com/manuals.nsf/websearch/AC6FAA69218C9624862567BD0061DDAC?OpenDocument&node=132100_US

Most likely the names and connec
tors on your drive may be slightly different, but you should be able to see the key connections that are required. For stepper drives, the key connections from the UMI will the be Step and Directions outputs.

The following KnowledgeBase discusses connecting a 73xx motion controller to a stepper drive:

http://digital.ni.com/public.nsf/websearch/CEC9025B2DD11B2786256CC400802D18?OpenDocument

Regards,
Michael
Applications Engineer
National Instruments

[mprover1]

I was told by the Gemini Rep that I only needed 4 or 5 wires from the Gemini to the UMI, those wires being Step +, Step - , Dir + , Dir - , and reset or shutdown. I dont see how Step +/- and Dir +/- correspond to Step(CW) and Dir(CCW) pins. I see two terminals that might be applicable , but have 4 wires. For shutdown/reset I assume I can use the Shutdown on the Shutdown terminal block

Thanks

JOsh

[mhaag]

Josh,

I apologize if I was not clear in the previoues post, but please take a look at the last link I posted in the previous reply. This will lead you to an article that discusses the Step +/- and Direction +/- connections. For most drives, the Step - and Direction - signals simply needed to be connected to the GND terminal on the UMI. Unless you have an optically-isolated drive, then this is the standard connection to be made.

Regards,
Michael
Applications Engineer
National Instruments

[Buechsenschuetz]

I do not agree completely with this post. We are using stepper motor drivers using a similar configuration of the step and dir inputs. I think on most stepper motor drivers using a step+ and step- (and dir+ and dir- respectively) input this means that they are using a differential input configuration. To drive such an input correctly, you need a ttl-to-differential output driver between the FlexMotion card and the driver. It is not stated anywhere in the UMI manual that the UMI provides differential outputs for these signal so I think you will need a ttl-to-differential converter with the UMI, too. The AM26LS31 is a well-proven IC for this purpose.

However, you should contact the manufacturer of your motor drivers to check whether
the inputs are true differential inputs, ttl level inputs or opto-isolated inputs.

[mprover1]

Thanks Buechsenschuetz,

Im not quite sure which direction to go . To those working at NI, does this seem like a plausable solution?

[mhaag]

Thanks for the input Buechsenschuetz. While I have seen plenty of customers who have been able to successfully setup there motion system by simply connecting their Step -/Direction - to GND, there are always special cases depending on the electrical properties of your specific drive.

The connection from the UMI 7764 to the Motion Controller (73xx) is a single-ended connection and most drives do expect a differential type of signal. By connecting Step + from the drive to Step (CW) on the UMI and then connecting Step - from the drive to Digital Ground on the UMI, you do create a differential connection for the drive. The drive will simply reference Step + versus Step - and come up with the high or low value of that input
.

I know I've given you a lot to look over but the following document contains some key information and diagrams of common ways to connect the 73xx to third party drives:

How to connect the 73xx inhibit and command signal outputs to third party drives.
http://zone.ni.com/devzone/conceptd.nsf/webmain/D474F58946FF8E4B86256DB20074803C?opendocument

If you have any more questions for us then please let me know.

Regards,
Michael
Applications Engineer
National Instruments

[Buechsenschuetz]

It is correct that a differential input compares the +input to the -input but there seems to be some confusion about the way a differential receiver does that.

The AM26LS32 data sheet (this is a very common differential receiver) says that in worst case this IC requires a differential voltage of +0.2V across the inputs for a logic high output and a differential voltage of -0.2V for a logic low output while they guarantee an input hysteresis of 30mV min.

Many, if not most, ICs will work with less differential voltage (the lowest value is not specified so let's assume it's 0V) which will be an explanation why most drives with differential inputs will accept the single-ended signal provided by UMI.

I
just checked the manual of one of the drives we are using which has differential inputs. They show a true RS422 (differential) driver to drive the inputs but also allow an open collector driver with one of the input lines tied to ground, as suggested by NI.

However, again, if this configuration does not work correctly on this specific driver I would suggest to contact the manufacturer for input circuitry details.