MLX 1400 analog in

[markdobtech]

I am perplexed. I am using an analog sensor output 0-10vdc into a micrologix 1400 analog in channel 0, there are no other analog inputs present. Using a scope at the analog input terminals, I can verify that the analog sensor is putting out a clean 0 - 10vdc as the sensor operates. However, looking at the I:0.4 contents in decimal format, the a/d conversion ranges about .2 - .4 vdc less than actual voltage at the terminal. Any ideas?

 

[kolyur]

The 1400's analog inputs are 12-bit so I assume you have the scaling set up as 0-10V = 0-4095 counts?

You indicate the error as volts DC... are you reading the ATD value and converting it back to volts?

The 0.2-0.4V you mention, is it an offset over the entire range or do you see that difference at the top end?

 

[markdobtech]

Set for 4095
Yes on conversion to vdc
0 difference on low. Differential grows as vdc increases.


Thanks for the reply.

 

[markdobtech]

I found the issue. It was my error setting up the scaling.

 

[kolyur]

Good to know, thanks for the follow up.