FieldPoint to change a polarity

[CBMM]

I need to change a polarity for a module when I need to do that for running another function. I have three modules (TC, PWM, and RLY) and Labview with PID toolset.

I've connected an external power supply to PWM module. The ouput of PWM can be changed by PID algorithm and connected to Relay module. I've wired four channels of RLY. The channel 0 and 2 used to get the direction from negative charge to positive one. The channel 1 and 3 used to get the direction from positive to negative one. The problem is how to operate this idea. It means that I don't tips or program to drive my application. Specifically, PWM output needs to be connected to two channels for each function. Thanks.

Tae Yoon Lee 

[Sean_C.]

Hello Tae Yoon Lee,

I am not sure that I understand your question.  Do you want to change the polarity of the output of your PWM module across a load with your RLY module?  Which RLY module do you have?

This would be easiest with the RLY-422.  With this module you could connect the COM lines from 2 channels to each side of your load, the PWM output to the NO lines, and the PWM ground to the NC lines.  Then it is a simple matter of having one channel closed and the other open, or vice versa to switch the polarity at your load.

This is also possible with the RLY-420, but would require 4 relay channels.  And you would need to make sure that Ch. 0 and Ch. 1 are never closed at the same time and that Ch. 2 and Ch. 3 are never closed at the same time.  This would result in a short circuit of your PWM.

Please see the attached diagram for an example of how to set up this configuration with either module.

Let me know if you have any further questions.

Regards,
Sean C.