analogue inputs

a.b.

Member
Join Date
Jul 2003
Posts
2
With a 0V-10V analogue input card is the positive common or is the negative common? Is there a analogue input card that reads a switching negative sort of like a npn analogue input card i suppose?
 
anything Steve you tell me ! How about hitachi or Mitsubishi oh and can you briefly explain the bipolar modules! thankyou
 
An analog input module reads the potential difference between two terminals. A bipolar module will have the ability to report both positive and negative potential differences.

In a twelve-bit module, a positive voltage might show up in the PLC as an integer value between zero and +4095, a negative voltage as an integer value between zero and -4095.

The spec sheets for the module you're evaluating should tell you if it can handle negative voltages.
 
Most commonly the -Ve side is expected to be grounded, to the same point as the -Ve side power supply and the card gives more stable results this way , lower noise ( you also get better results if ground both sides of unused analog inputs on same card) but both should be able to float so long as they dont float higher than the isolation value of the card.
 

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