Problem with write subvi in Watlow EZ-Zone controller

[Watlow]

Is the Watlow driver being used on a Windows PC machine or a standalone NI device? The driver uses a Windows dll to communicate to the EZ-ZONE PM device which would not work on an embedded controller.

Best regards,
Watlow Technical Support

[garciaj]

Hi, I did not use the NI9871 module and I do not have experience working with it, so I am afraid I cannot help.

[Sumon_Davis]

Hi,

Thanks for your reply. 

The watlow driver was installed on windows PC not with any standalone NI device. We are using NI 9149 expansion chassis Ethernet type to add the C-series modules (NI 9871 and others). You know the reason we are using 9149, is we need to add 6 different, modules for collecting real time Temperature and relative humidity  information of grains, desiccant, and air and based on the condition of temperature the heater will be operate and to control the heater automatically we want to use EZ-ZONE PM coupled with NI9871 module via LabView.  I am now wondering whether NI 9149 is compatible to communicate with EZ-ZONE PM device or not. If not, then could you please let me know your suggestion/ the possible alternative way. 

Looking froward to hear from you.

Regards,

Momin

[Watlow]

Try closing LabVIEW and execute the EZ-ZONE Configurator software to speak to the PM controller using the NI hardware. If the NI hardware is simply acting as additional serial ports visible to Windows, the  software should work. If Configurator will not speak to the PM, then the hardware appears to be incompatible to the PM.

Watlow Technical Support

[Sumon_Davis]

Hi Garciaj,

Thanks for your reply. I got your point. So for your project, you used an USB to RS 485 adapter to communicate with EZ-ZONE and Labview, am I right? If I want to do the same then except the adapter do I need any other device? I was wondering whether is it possible to share your VIs for my understanding. 

Thanking you again and looking froward to hear you.

Regards,

Momin

[Watlow]

Yes, Watlow uses a B&B Electronics EIA-485 to USB converter, The latest VI is located on the Watlow web site that addresses the C-F issue you experienced earlier. The detail in the dll is not released but the rest of the VI example is visible.

Best regards,

Watlow Technical Support

[Watlow]

To answer the other question, nothing else is required to communicate to the PM other than the EIA-485 port.

[Sumon_Davis]

Hi,

Thanks for your reply and the suggestions. After did several research I came to know that I was playing with wrong hardware combinations NI 9149 and 9871 for configuring the Watlow controller. I decided to buy 485USBTB-2W converter and placed order at B&B electronics. I believe this will help me to communicate the controller using LabView. I will keep you update.

Regards,

Momin

[Sumon_Davis]

Hi,

Greetings! In April 2019, I had contact with you regarding watlow  EZ-ZONE PM-6 controller configuration with LabVIEW. Per your guidelines I am now able to talk (controlling my heater temperature at certain condition) with the controller as per my requirement using the Initialize and Write VIs. But since I did not include the close VI so every time I stop my LabVIEW program I am getting crash error report. I think it is because I am stopping LabVIEW program before stop/exit from the controller, which I need to address first.

Hence I have included the close VI (pls see picture 1) into my program and that allow me to stop the controller first (by hitting the created close button in the front panel) and then able to stop the LabView program without getting any crash report. But after adding that I think the write vi for controlling the temperature is not working and getting error message (please see picture 2). I think there is something wrong with my connections or missing the sequence, which I was not able to figure out last couple of days. I will highly appreciate your help and suggestions for fixing this issue. 

Another thing is it possible to close the controller only when the certain/desired condition has reached to avoid the temperature effect on other parameters, while continue running the LabVIEW program.  

Your help would be very much appreciated in this regard. Thanking you and I am looking forward to hear from you.

N.B. I'm sorry for long post!!!

Regards,

Momin

UC Davis

CA

[Albert.Geven]

You forgot that in LabVIEW wires determine the order of execution, not the position in the block diagram.

Your close is now executed in parallel with the main while loop, probably before the write.

Wire the green line from inside the main while to the close system vi and you probably get the write working again.

Also do not use the "wait until next ms multiple" for just waiting because that sometimes waits 0 ms when activated just before the system timer ticks. Use the "wait ms" instead. The one with the watch.