Analog Signal Types

[The Plc Kid]

I am trying to understand all the various analog signal types and where and why one would be used opposed to another.

I am well versed at 0-10 and 4-20 but i have some stuff that is +/- 10 VDC how does this work and why would you use it vs 0-10? I see it i hydraulics controls quite a bit.

 

[sthompson]

You will see it when you need bi-directional control. In Hydraulics, I would imagine they are moving the shuttle back and forth to change the speed and direction of a hydraulic cylinder or motor. Most VFDs will allow you to change from forward to reverse by using a bipolar signal.
Hope that helps.

Stu.....

 

[palithad]

You can use it to bidirectional control in hydraulics or reverse a small DC motor via analogue output. When the polarity of the voltage changes the direction of the motor changes provided sufficient current can be directly drawn from the PLC output.