Releasing serial ports to other applications

[patrickokeeffe]

I've made a button component which launches some third-party software for initially configuring an instrument but since it's a serial device so I need to release the COM port first. Setting the port to zero and reinitializing should do it right? Here's my button code:

lastLicorComPort = Device.LI7500.Port  // save & restore after config
Device.LI7500.Port = 0				 // set dummy port
Device.LI7500.InitComm()			   // make the switch
delay(1)							   // catch up computer (?)
System.ShellExecute("LI7500.exe","open","","C:\Program Files\LI7500v3_0_2\","")

...should work right? The port stays locked up though. Not the utility, nor a terminal program nor even the Safely Remove Hardware icon are able to get through. Am I missing a detail somewhere? I certainly don't want to shut down my whole data acquisition system to configure just one of the instruments. Any help is appreciated.

[AzeoTech]

Try setting it to an non-existant port # instead, say port 21.

[patrickokeeffe]

I went ahead and tried using non-existent ports like 21 & 36 - DAQFactory threw the error 'Unable to initialize Com...: Can't access port, probably in use by another app" in each case. Perhaps I need a real, but still available, port to switch to?

[AzeoTech]

Nah, just let it throw the error. Just ignore it.

[patrickokeeffe]

Using the device configuration dialog, I changed the port # to an unused physical port and went to the monitor window: incoming data stream from the first port keeps coming in. Setting to zero doesn't work, nor does setting to non-existent COM ports so there is no way to release a com port without quitting DAQFactory and waiting for the process to finish?

[AzeoTech]

No, there's something else going on here. Do you have other serial ports listed in your Serial/Ethernet configuration window? Did you open up any old drivers, like the old Modbus driver? Maybe you can post your .ctl doc?

[BeeHay]

Would it help anything to do a Purge() first?

Just a thought.

[AzeoTech]

No, that would just clear daqfactory's internal buffer.