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

[FLiu]

So Google search suggest that Baud Rate in VISA Read and Write needs to be changed to match the settings in NI MAX. Am I heading in the right direction ? How would you suggest me to do that ?

Thanks

Felix

[Dennis_Knutson]

I'm confused by the Initialize function. From your image, I don't see anywhere that there is a write of the *IDN? and what is returned is a byte array. Sorry, I don't have the chamber/controller to say what is wrong but it appears the driver is not configured for your setup. The driver looks more like Modbus.

[Dennis_Knutson]

I just noticed that your message topic includes the word modus. If you can use the *IDN? query, it is not modbus so either you have create a new driver for the protocol that is currently configured or change protocols.

[FLiu]

This is the Driver that I got from NI. http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=0150785855373A2DE0440003BA7CCD...

It says Serial Interface and I am using Serial Connection on the Communication Board. I am not sure what I am missing. Could you clarify ?

Thanks

[Dennis_Knutson · Accepted solution]

The driver was written for a watlow that uses the modbus protocol. Apparently yours does not use that. Modbus does not use ASCII text for sending commands our receiving data. It is all hex. It does not support GPIB, either. Yours is definitely not Modbus because you are able to send the ASCII text *IDN? which is a GPIB standard command. The driver simply does not match up with the controller you have.

[FLiu]

Thank you for your reply. The *IDN? command was sent to the Tidal Engineering Synergy488 Board which has serial and GPIB connection on it. That was where I succeeded in communicating in NI MAX. The Watlow manual only contains ModBus Commands. The Synergy488 Board manual does not contain any SCPI command or serial command that I can use to program. I am little confused.

[Dennis_Knutson]

I'm confused as well. You said the synergy board is connected to the watlow. How and why?

[FLiu]

When we bought the Chamber. We specify that we want GPIB and Serial Communication. The Watlow F4 communicates using ModBUS. So the manufacturer put a Synergy488 board there to enable serial and GPIB communication with PC. So the Watlow connects with the Synergy 488 Board and the Synergy board connects with PC

[FLiu]

I was able to write and read register using a simple serial VI. You are right that Watlow Driver was not written for my application.

Thank you so much for your help.

Felix