Author Topic: Analog Input self incrementing  (Read 11141 times)

rbatta

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Analog Input self incrementing
« on: March 27, 2011, 10:11:33 AM »
I have a T100MD888 with an iSnail 0-5VDC CT.  I have the positive terminal of the CT connected to AD Pin #5.  The Negitive terminal is connected AD Ground.

There is a steady 2V reading on the terminals of the CT.

I have a 1 second clock circuit that updates the ADC(5) reading.  When the PLC restarts, the reading starts near zero and increaments by 8 until it reaches 4096.

What am I doing wrong?
 


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Re:Analog Input self incrementing
« Reply #1 on: March 27, 2011, 10:16:36 AM »
Sounds like you may have connected to the wrong pin? Note that ADC1 is on PIN8 and ADC2 on PIN7 and so on. So ADC5 is on PIN 4.

If you have connected correctly, did you measure the voltage on the ADC5 pin?

Also can you check your ADC reference voltage. Is it at 5V. If not, check the AVcc Cal potentiometer to get 5V.
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rbatta

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Re:Analog Input self incrementing
« Reply #2 on: March 27, 2011, 10:22:28 AM »
Thanks for the quick reply.  I'm a dummy, you are correct, I was looking at the wrong channel.

Thanks again.

Rob