3 posts in this topic

Dear Friends;

Today i am stuck and do not understand how i fix the following issue?

1. We have PH controller from Hannah Model HI 8711T , PH transmitter HI 8614L and PH probe. On the terminal blocks of the controller there are  4-20mA (Isolated). 

2. We have FX 2N-4AD analogue module to read the PH value on the HMI.

3. First i connect the 4-20 mA as follows

Short the V+and I+ terminals and connected it to the -ve of the controller 4-20mA terminal.

I- connect withe the -ve of 24 VDC. and +24 applied to the +ve of controller 4-20mA terminal.

But the reading not read by the controller.

Then i change the wiring as follows

Short the V+and I+ terminals and connected it to the +ve of the controller 4-20mA terminal.

I- terminal connected to the -ve of the controller 4-20 mA terminal.

By this the reading is shown perfectly.

But the issue is after 10 to 15 second all the values that is on the LCD of controller , transmitter and on HMI fluctuate. Even i connect and disconnet the shield on the Module side but the issue is not fixed.

How i fix it, and guide me how i wire up properly FX2N-4AD with 4-20 mA isolated output of the controller?

 

Thanking you, I will remain 

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Did you set up the module in the PLC? The is an analog edition of the programming manual that has details about how to do this including programming examples.

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Hi Dynamicboy,

Attached a wirering diagram for 4-20mA at a FX2N-4AD module.

Also a programming example how to make an average reading if you signal is fluctuating too much. Aldough I think you might pick up some noise in the wires.

If you have a loop generator in your workshop you can simulate a 4-20mA signal at the input of the PLC to see if the problem is present inside the PLC module or programming or if the problem is inside the Hanna transmitter.

 

Best regards,

Theo V.

FX analoogsignaal gemiddelde waarde.JPG

FX2N4AD.jpg

loop-power.jpg

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