Watlow F4D Serial Communication Problem Error Code -1073807339 VISA Read in Watlow F4.lvlib:Utility MODBUS RTU Receive Message.vi

[FLiu]

Hi

I am trying to communicate with a Watlow F4D controller on a Chamber using RS232. I use a USB-Serial Converter Cable and NI Watlow F4D Serial Driver.

The error code -1073807339 occurs in :

VISA Read in Watlow F4.lvlib:Utility MODBUS RTU Receive Message.vi->Watlow F4.lvlib:Utility Read From Register.vi

I am not sure what caused the issue. I am able to see the USB-Serial Converter Cable in NI MAX. Please see pictures for details

Thanks

Felix

[FLiu]

Please see picture attached for more details. The errors occurs mainly at VISA READ in Receive Message.VI

Thanks

Felix

[Dennis_Knutson]

You'll only get a timeout when doing a read.

You should check to see whether your cable is correct.

[FLiu]

Thanks for your reply. The cables are working. I used the USB-Serial converter and the Serial Cable on other instruments before.

[Dennis_Knutson]

Unless you used the cable on another watlow, whether it works or doesn't work with another instrument is totally irrelevant. RS-232 does not standardize on cabling in any way.

[FLiu]

I tried two other serial cable. I got the same time out error. The Modbus communication board has both Serial and GPIB connections. I tested both connections in VISA test panel. I was able to get *DIN? information using the GPIB connection. I was not able to get *DIN? information using the Serial connection. A time out error occured. What should I change in VISA property nodes in the Watlow F4 Serial Driver to enable GPIB communication ?

Thanks

[Dennis_Knutson]

You aren't supposed to just try other cables. You are supposed to look at the cable requirements in your manual and then check your existing cable with a meter.

What is *DIN? Do you mean *IDN? Sorry, I don't have the driver to look at. What have you tried?

[FLiu]

The communication board connected to Watlow F4 is Synergy488. I tested the RS232 connection using an application provided by the company. I was able to get response for the *IDN? command. Does this prove that the cable is working and there is something I need to change in Labview driver ?

Please see pictures for detail

Thanks

Felix

[Dennis_Knutson]

Yes, that does show your cable is correct. Have you tried a \r (carriage return) as the termination character?

[FLiu]

Update :

I was able to get *IDN? response in NI Max it turned out to be syntax error. It should be *IDN?\r\n instead of *IDN?\n. I changed Baud Rate Setting in NI Max to 19200 and tried to run the VI. I still got the same error at VISA Read...