Voltage to Resistance???

[Scott]

I have a PLC that is around three years old and would like to add a few more sensors. I have no more comm ports but spare analog inputs. I would like to try to do this with a couple of wireless transceivers. It will be very difficult to get any cabling to each sensor.

I would like to have a PIC read the sensor such as pressure, temp then wireless transmit its value to the remote receiver. The receiver will need to use a table or math conversion to reproduce the resistance of the sensor for interfacing with the analog inputs on my PLC.

I have been thinking about using multiple digital pots to covert the value back to resistance but it will take a couple pots to reproduce the curve for the sensor.

Are there any voltage to resistance converters that might work for this?

Any help would be greatly appreciated,

Scott

[Melanie]

Most commerical PLC's (eg Trend) will accept a 0-10v ADC input. Pretty simple to PWM a 10-bit resolution value to simulate your Sensors range. Search the forum for "0-10v" for a voltage doubler circuit.