pH & motor on/off data logging

gtosaya · Post by **gtosaya** » Fri Jun 27, 2003 12:07 am

I would like to record wastewater pH (0-14) and when the discharge pump runs (on). The pH probe is connected to a transmitter that has a 4-20mA output. The pump voltage is 115 VAC and 2.1 amps.

Possible sampling rate: 1 sample per minute.

markspencer · Post by **markspencer** » Fri Jun 27, 2003 7:32 am

Hi,

To measure these you need a unit that has a minimum of two channels, can measure bipolar voltage.

The simplest solution is to use the ADC-100 this unit has two channels measures voltage in the region of ±20 volts and has a sampling rate of 50ksps for each channels while both are active.

To measure the 4-20mA you would have to use a shunt resistor to give a voltage that can be feed into the ADC-100. Once this has been completed a scaling file would have to be used to display the voltage as a mA reading.

http://www.picotech.com/40_42_100.html#adc100

To measure the voltage, since it is above the low voltage directive you will have to use an x10/x100 isolating probe.

http://www.picotech.com/accessories.html#x100

Picolog software would be used to measure log the data and is supplied free with this unit, with upgrades to the software available form our website.

Best regards,
Mark S.