USB to 422 Converter Woes

[Jim_Flip]

I have a USB to RS422 converter that was packaged with an IMS MDrive 23 stepper motor controller. I probably should have bought the NI Converter as I can’t get LabView to write to the port. The device is nicely packaged with a driver that makes it appear in Device Manager like a standard serial port. M&A Explorer seems to like it and will open a VISA session.

I can’t get past the LabView standard VISA Write command. It issues a “Could Not Perform operation because of an I/O error" or a “The specified attribute is not defined or supported by the referenced resource" error. When I reboot the motor controller, it issues a “reboot successful“message that can be read from the port from LabView, so I am communicating with the port and controller in one direction. Without changing anything, HyperTerminal communicates successfully.

Any ideas will be cheerfully and thankfully appreciated.

[Brian_Beal]

I have used the IMS converter with Labview, but only to test basic comms.  If I recall, it echoed back the command, but I believe that can be disabled in the MDrive.

[Jim_Flip]

Thanks Brian! Is there a chance you could post this as a 8.0 or even a 7.1 format? I haven't upgraded to 8.2 yet and our IT department didn't pay the maintenance fee.

Many Thanks!!!

[Brian_Beal]

I can only go back to 8.0.  Here it is.

[Jim_Flip]

Brian,

Words will not describe how greatful I am for your assistance. I have been screwing around with this issue all morning and haven't even made the motor move once...until now!

Thanks Again

Jim

[Brian_Beal]

Jim-

Your welcome.  I have been screwing around with an MDrive 17 all afternoon, and am very frustrated.  I am not using the IMS converter, but a different brand.  I have used this converter for years with many devices and different programs, but the MDrive doesn't like it.  I hate to say it, but you are probably better off with the  IMS converter.

Brian

[Jim_Flip]

Brian,

I am now cruising along with the 23. Whatever I was doing was so subtly wrong, I could not guess what the problem was. It was something with the termination characters --  but I have never had a problem like this before and have used many USB converters. The folks at IMS were helpful, but would not offer any advice on LV except to say it was a VI setup problem.

DUH...

I have never used an advanced controller like this before and  now have to learn the Motor language and try to get the stepping rates correct, but that will be the fun of a new challenge.

Thanks Again,

Jim

[Brian_Beal]

Jim-

I have to correct you on one statement.  The IMS is not an advanced controller.  It is about the most basic, and I only use it for simple applications that are not "mission critical".  It is an OK one to learn on, but is only somewhat like other motion controllers.  The language is limited in what it can do.  Let me know if you have any other questions about it.

Brian

[Jim_Flip]

Brian,

It is advanced -- but only from my own perspective. My last motor project used two motor chips where the only inputs were frequency (speed) and current! IMHO.

This device is a marvel of modern science ;-D

Jim

[Swamp Thing]

Brian,

Thanks for the posts and VI. I grabbed your "IMS Read Write.vi" and it works for me. However, when I simplify it by removing the "Read" part of it, "VISA Write.vi" returns an error, even though the Write comes before the Read. Any clue what's going on and hints how I can get an error-free write-only function working?

Thanks, Chip