rt usb-232 device not configured properly

[Tom_Sz]

I have a serial instrument (19,200 Baud, 8-bits, no parity, 1 stop bit) which i would like to use in an Real time (PC) system. Sending a command "81B1\r" will return in the buffer " 0001.4\r" or 8 characters. I am running MAX 5.0.

a) Connecting the device toa serial port ona NI-232/8 card on "My System" PC gives the proper response in the VISA connection.

b) Connecting the device using a USB port through NI USB-232 dongle generates a USB - Port 1 entry and maps it to a COM5 port. Opening the VISA in Com% gives the proper response to the query.

c) Connecting the device to the remote's USB port (The remote was verified to be compatible with RT 2011) Creates a port "USB0:0c3923:0x703c::NI-VISA-0::RAW" Setting VISA alias on My System to COM19 and VISA alias on remote as COM5. Opening the VISA panel under attributes gives the following error: ATTRIBUTES - VI_ATTR_USB_CTRL_PIPE, VI_ATTR_USB_BULK_IN_STATUS, and VI_ATTR_USB_INTR_IN_STATUS has the message "Invalid Property Value".  Under USB Settings i have Control Pipe - Default (0); Bulk in pipe - No pipe present; and Bulk out pipe - 01. None of these are changeble - gives an error.

Has anyone come accross this and solved it? - Thanks

[PeterGC]

Tom,

In part c, am I correct in thinking that you are plugging the USB directly into the RT computer?    

Here is a document I found describing how a USB can be controlled in RT.   I will continue to monitor this forum and try to see if I can get some more information for you.

http://digital.ni.com/public.nsf/allkb/5F30CD20D4D986CC862576CF00748B15?OpenDocument

[Tom_Sz]

Hi Peter,

Yes, I plud directly in the back of the computer's USB ports. I have also tried the Serial port COM1 directly from the instrument. The port is valid in MAX, but times out. Are any NI solutions a better bet?

Thanks

Tom

[PeterGC]

Tom,

Could you provide me with a little more information?    I know you are using a USB-232 and it is not communicating with your RT device properly, but what exactly are you trying to do?  

There may be a better solution, but I need a little bit better of a broad system understanding to make any recommendations.

Regards,

Peter

[Tom_Sz]

Hi Peter,

What I am trying to do is to keep a constant tension on a piece of glass capillary tubing. I have a PCI-7340 motor controlloer on the RT system and the serial device feeding through the USB-232 giving a tension value. The tubing has a small furnace heating it, thus allowing the glass the stretch. as it stretches the tension drops and the motor will move up to get the tension to its desired value within +/- 0.5 grams.

I might hava a possible solution, which I will try out soon. It is possible to get an analog out signal from the serial device, which I can feed into the analog in of the motor controller and should be able to read it via LabView.

Thanks - Tom

[PeterGC]

Ok, sounds interesting.

Keep me updated.

[Tom_Sz]

I finally got it to work - instrument output 0-10v gives the 0-2.5# range. The 7340 analog in gives a 0-4095 bit resolution for the 0-10v and several hundred samples/sec in the RT. Read out by the host is only a couple of samples/sec using the "host vi..vi" & "target vi.vi"type vi. What is the best TCP communications between host & target?

Thanks

Tom