Device finder using COM or GPIB

[Mr. Robert]

Hello, I have some HP 34401A DMMs, I want to use a single VI to Check their IDN Address; assume I I don' t know the real address they are being set.
It used to idenify are there any devices are offline or ready to use and show the READY DEVICE in a Device list and there Connection using COM / GPIB.

It  auto check the port in every minute.

[smercurio_fc]

If I understand you correctly, you want to find out how to get a list of instruments. Ue the "VISA Find Resource" function. If you read the help on it you will see how to use it. By default, with nothing wired to it the function will return all resources it finds. You can then parse the list to find out what's out there.

[Makoto]

VISA Find Resource function does enumerate the active GPIB addresses and available Serial (COM) ports, but the conditions are different between GPIB and Serial.  The found GPIB resources are what truly connected online, but found Serial resources are the ones just recognized by OS.  For example, if your PC equips COM1 port and Windows recognizes it, the Find Resource function always include "ASRL1::INSTR" in the enumeration result even if the instrument is disconnected.  To check the existence of instrument on Serial port, you must perform real I/O operation such as send *IDN? and receive its response.

The other solution for deciding actual VISA address at runtime is use "Alias" feature of VISA.  By using it, your app only need to design to include an "Alias" address such as "DMM1".  At runtime, adjust VISA alias configuration for the target PC by using NI-MAX such as mapping the alias address to "GPIB0::1::INSTR" or "ASRL1::INSTR" or any you want. 

このメッセージは　07-18-2007 09:39 AMに Makoto が編集しています。

[BIRA_PXI]

HI,

I am using an Oxford Semiconductor PCI to UART card which has two COM ports ( COM0 and COm1). When I install the card, I just want one of the COM ports to be visible under the VISA REsource Name to the end-user, I:e either COM0 or COM1 and not the BOTH of them. How can I do this in Labview ?

Any input is appreciated.

Thanks,

bira_pxi

[Dennis_Knutson]

Instead of a front panel VISA Resource Name control, you can use the Find VISA Resources, edit the string and populate a list box. You could also delete the alias of one of the ports and with the I/O filtering of the VISA Resource Name, uncheck the "Include resources that do not have aliases". You might also be able to delete a port in windows device manager but that's something I haven't tried.

[BIRA_PXI]

Thanks Dennis.

Bira_pxi