Analog Inputs negative voltage

[hellpingui]

Hi,

I would like to know if the analog inputs accept a negative voltage (eg -400 mV to 400 mV).
This voltage is provided by a PH probe


thank you in advance for your answers

Sorry for my English 

Damien (France)

[jason]

I don't thin that will work. The analog input pin is 0-5v only.

A potential work around is using the +5v and ground pin of an I/O channel to power a 2.5v regulator.  Then connect the PH probe ground wire to the 2.5v voltage regulator output instead of the IO-204's ground.   This way the IO-204 will measure the voltage range as 2.1v to 2.9v.

There are many 2.5v voltage regulators to choose from. Here is an example:
http://www.national.com/mpf/LM/LM2937-2.5.html#Overview