Hello,
I am new to the PLC and electronics world. So please bear with me.
My question is concerning the hookup of the T100MD-888+ PLC to a motor driver (MD2S-P)
http://www.usdigital.com/products/md2s/In the MD series Installation manual it suggests to use a current limiting resistor to make the PLC compatible with the motor driver's 5V inputs.
I did the math as per Page 9 of the manual (
http://www.tri-plc.com/MD-man.pdf)
It is my understanding that this is because when the PLC is logic low, it pulls up to +24V. So the stepper driver would experience a very large current flow if it was not restricted by a resistor.
Calculations:
Given I_f = 5.5mA
(24-5)/0.0055 = 3454 Ohm.
So all that I would need is a 3.6k to 3.8k resistor for each line to limit the logic low current from the PLC to the stepper?
Also, is this "opto-isolated" as they suggest as necessary?
Any help would be greatly appreciated.
Cheers,
Kevin Li