Ron Beaufort
Lifetime Supporting Member
http://www.plctalk.net/qanda/showthread.php?p=14314&postcount=3
this should get you going ... when you calculate the needed resistance, don't forget that the input module will add 250 ohms to the circuit ... if you've got a 24VDC power supply, you can skip the batteries ... and the SLC-500 power supply probably has a set of 24VDC terminals built in ...
note that some Radio Shack pots that are marked 5K might be at the high or low end of the tolerance range - so you might not be able to go all the way from 4 to 20 milliamps ... but you still should get enough of a range to make for some interesting experiments ...
if you skip the box and the batteries, then less than $5 or $6 bucks should put you into the "analog input" game ...
this should get you going ... when you calculate the needed resistance, don't forget that the input module will add 250 ohms to the circuit ... if you've got a 24VDC power supply, you can skip the batteries ... and the SLC-500 power supply probably has a set of 24VDC terminals built in ...
note that some Radio Shack pots that are marked 5K might be at the high or low end of the tolerance range - so you might not be able to go all the way from 4 to 20 milliamps ... but you still should get enough of a range to make for some interesting experiments ...
if you skip the box and the batteries, then less than $5 or $6 bucks should put you into the "analog input" game ...