Watlow F4 Controller with LabView

[elew90]

I just tried adjusting the timeout delay and it doesn't fix the error. Is there a better way to set and track the setpoint temperature? I choose the insert time ramp.vi because it sets the setpoint directly and then I had it be monitored in the while loop to see if the temperature actually went to that.

[Catherine-B]

Hi elew90, 

Are you using the Watlow F4 instrument driver or the Modbus library? Looking at the error message you attached, it looks like a VISA error, but it looks like the error is occuring in a Modbus VI.

[elew90]

Hello Catherine,

I am using the watlow F4 drivers. I actually got a little further with the program but now the issue is trying to set the temperature setpoint. It turns out the examples they have in the watlow library mostly work for profiles and that conflicts setting the event outputs. I attached my code. So far I've been able to turn on my chiller unit by setting digital output 1 high and turn on the compressor unit to cool the temperature by setting digital output 8 high.

I've been looking into the Insert Ramp Time Step.vi in the watlow f4 library to see if there's some idea to get the setpoint problem fixed.

Thanks,

Eric

[elew90]

Basically I want to create a setpoint manually without using a profile and have the chiller run until it reaches that setpoint and soak there until I change it again. Along the way, the chiller will either heat up or cool down depending on what the current temp is.

[Jason-H]

I downloaded the wlf4 driver from here, but I don't see where you got the express VI's from...

[elew90]

The different vi's I have in my code are taken from the watlow f4 library that you downloaded from. I first looked at the examples that were provided to see how the different files ran and what they did. Then I just took the ones I needed for my application. The vi's are all there.

[Jason-H]

Okay, so just to make sure I'm understanding correctly, you are successfully communicating with your device? What exactly do you mean 'the chiller will either heat up or cool down depending on what the current temp is.'? Are you referring to the ambient temperature? Can you open the profile it is currently using to see what it is doing?

[elew90 · Accepted solution]

I am communicating with the controller correctly. What I meant by heat up and cool down is that the chiller recognizes that the current temp is not the same as the setpoint temp I created. It will move towards the setpoint temp like a thermostat and when it reaches the setpoint, it will stay there until I change it again.

I have solved the setpoint problem. I will post if there are any other problems. Thank you!

[KumarAVA]

Hi elow90,

i am trying to do exactly same thing what you are trying to do. 

i am also using Watlow f4 drivers.

i am getting the same Error -1073807339 at  VISA read in WLF4 Utility MODBUS RTU Receive Message.vi

how did you solve this error? 

Regards

Kumar

[Ryan_K.]

Hi Kumar,

As mentioned earlier in this thread, that error is a VISA timeout error. A good first troubleshooting step would be to make sure that you can communicate with your device at all. Try opening a VISA Test Panel in MAX (right click on the device and select "Open VISA Test Panel" and try sending a simple *IDN command.

If that fails, check your setup to make sure eveything is connected properly. If that succeeds, I have a few additional questions:
- What version of LabVIEW are you using?
- What version of NI-VISA are you using?
- Have you ever been able to communicate with the device using the driver?

You could also try using NI I/O Trace to capture the calls to the VISA driver. This might give you more insight into what's going on when the communication is timing out (what particular command is being sent, etc).

Regards,