Instrument Control (GPIB, Serial, VISA, IVI)
Random 1073807360 error in Configure Serial Port.vi
Hi,
I've been getting a random
VISA "Unknown System Error" from attempts at serial port communication in a machine automation program I've written. I'm running LabVIEW 7.1 with NI-VISA 3.1.
The program is in contact with several serial interfaces. One of these is a Microchip PIC18F4550 CDC USB driver that is accessible via COM7. The other two serial devices are serial COM ports connected via USB-to-serial port hardware.
For starters, the read-write VIs that I wrote for these three serial devices have all followed the mold of the basic serial read/write example VI--i.e., they run "Configure Serial Port.vi" and VISA close every time. These read-write functions are run inside the main program very, very often. I've seen hints that this is a bad programming tactic on these boards without explanation as to why, but I am preparing to test if just leaving the ports open eliminates the random errors since I don't need anything but LabVIEW to access the COM ports while the system is running.
That said, the 1073806360 misc. error occurs randomly after anywhere from 1 hour of program up time to every several hours, and sometimes entire 8 hour runs can be completed without the error occurring. The error has thus far always occurred when trying to access the PIC on COM7 with the CDC driver.
After the error occurs, in MAX COM7 has the yellow exclamation point and can't be access with VISA. There is no error in Device Manager. Unplugging and replugging the USB cable to the PIC allows the VISA resource to reset since COM7 disappears and then reappers in Device Manager when the PIC cable is reconnected.
My question mainly is: what could be the cause of the random 1073807360 error based on what VISA is doing? I already checked the stop bits issue in the KB, and that is not the problem since the default values are used. Also, what is the proper way to handle VISA serial in large programs like this (and what is the problem with rerunning Configure Serial Port.vi/Visa close often)?
Thanks very much,
Scott
I've been getting a random
VISA "Unknown System Error" from attempts at serial port communication in a machine automation program I've written. I'm running LabVIEW 7.1 with NI-VISA 3.1.The program is in contact with several serial interfaces. One of these is a Microchip PIC18F4550 CDC USB driver that is accessible via COM7. The other two serial devices are serial COM ports connected via USB-to-serial port hardware.
For starters, the read-write VIs that I wrote for these three serial devices have all followed the mold of the basic serial read/write example VI--i.e., they run "Configure Serial Port.vi" and VISA close every time. These read-write functions are run inside the main program very, very often. I've seen hints that this is a bad programming tactic on these boards without explanation as to why, but I am preparing to test if just leaving the ports open eliminates the random errors since I don't need anything but LabVIEW to access the COM ports while the system is running.
That said, the 1073806360 misc. error occurs randomly after anywhere from 1 hour of program up time to every several hours, and sometimes entire 8 hour runs can be completed without the error occurring. The error has thus far always occurred when trying to access the PIC on COM7 with the CDC driver.
After the error occurs, in MAX COM7 has the yellow exclamation point and can't be access with VISA. There is no error in Device Manager. Unplugging and replugging the USB cable to the PIC allows the VISA resource to reset since COM7 disappears and then reappers in Device Manager when the PIC cable is reconnected.
My question mainly is: what could be the cause of the random 1073807360 error based on what VISA is doing? I already checked the stop bits issue in the KB, and that is not the problem since the default values are used. Also, what is the proper way to handle VISA serial in large programs like this (and what is the problem with rerunning Configure Serial Port.vi/Visa close often)?
Thanks very much,
Scott
