remote printing in LV6.1

[pawel]

Hello All

I need to controll the remote device with LPT connector. Normally it is connected to the local LPT port and there is no problem.
Unfortunatelly this device must be separated from my computer at a long distance but I still need to use it.
I know that it is possible to use some transparent ethernet, but I can not find any ethernet <-> LPT converter, which will create a virtual LPT port in my machine. All I could find is the printer servers, but their software does not create virtual LPT. They are meant to support the remote printing by means of windows software. My device is not a printer and I need LPT port, which will be reported by MAX and VISA as the standard LPT.

Can somebody help?

thanks in advance
Pawel

[Dennis_Knutson]

How far away is the printer? Black Box" sells extenders for up to 4000 ft. They might have other solutions available. I have found them very helpful and knowledgleable and it might be worth a call to their tech support line.

[Randy_H]

Pawel,

Another idea is to create your own TCP interface in LabVIEW. If you have multiple licenses, you can use a second copy of LabVIEW, or if you don't, you can create an executable if you have the Application Builder. Your remote application will listen for TCP messages and do what it needs to do and send back the results. Your client program (on your machine that you are sitting at), can have a choice of command to run and send those to the remote application.

Another method would be to use remote panels with LabVIEW 6.1 and have your remote application act as a remote panel server. In this case, you could just bring up the panel of the remote application and run it as if it were connected to your machine. There are some limitations of using things this way
(like saving files would have to be done only on the remote machine), but this might work for you as well.

Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask

[pawel]

Hi Randy

The whole idea of my system is to use only one PC and connect to the electric-mechanical devices only with one ethernet cable. I have 4xRS232 devices, 2xLPT devices and also some general I/O devices. For RS and I/O I have found ethernet controlled interface. They hav a special driver, which install special virtual COM ports in the system. So writing to the virtual COM port you control your RS232 device, which is hooked up to the ethernet.
The only problem I have is with LPT devices controlled via ethernet, which will report their existance as a virtual LPT port in the PC.
regards

Pawel

[Randy_H]

Pawel,

I don't think there is anything we can do for you then since it would be the remote driver's responsibility to register the LPT port as an actual port and not a virtual port. I am sorry.

You should be able to call into the driver DLL to do what you need. This would require looking up in the manual the function calls you would need to make.

Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask

[pawel]

Hi Randy

I am not sure. What I am looking for is the kind of device I have for RS232, LPT but unfortunatelly for USB. The device you plug into your USB port, and install driver for this device. The driver creates virtual COM and LPT ports, so the ordinary programs can send the information to those ports in the same way as they send to onboard ports.
The problem is that I want this device on ethernet not USB. I have already found the solution for RS232 ports. The device is called printer server and has 4xRS232. It also has 1xLPT, but this can not be mapped as LPT port, but requires to map it as TCP/IP printer port, which does not work for me. Anyway the device for RS232 already exist and the only one I am missing is the LPT.
regards
Pawe
l

[Randy_H]

Pawel,

I am not sure what else to say. There are many parallel ISA or PCI cards that you could use to do this as well instead of the USB device. LabVIEW needs to access registers of the parallel port to work correctly. The mapping that you have at this time will not work because of this. I am sorry that I do not have abetter solution for you at this time.

Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask

[pawel]

Hi Randy
Thanks anyway. I have also another idea with serial to parrelel converter. I did not try it yet, but I have bought the converter and I will try it very soon. The converter is very cheap ($20) and should vork for me since my device needs to be controlled very slowly (it is 255 channel mux). Maybe it will work. The only thing whioch woory me is the race problem. Unfortunatelly, the mux detects change in CLOCK line and take the DATA line. When pluged to LPT the task was easy. I could controll every line separatelly. I am not sure how the RS->LPT convert every 8bits, whether it will change only the one line or change all to zero and set them again to what is stated in the control word. But that is what I will find very
soon :).

kind regards
Pawel