Using the jrk21v3 to measure motor current


I’m having trouble getting my jrk21v3 to measure the current consumed by my motor. Using the configuration utility, I’ve got the jrk and the motor set up so that I can use the slider to control my motor’s position. On the Motor tab, I’ve set my max current to 0.15A and I’ve left the current calibration at the nominal value of 38mA/bit. On the Error tab, I’ve enabled the max current error.

Unfortunately, on the plot window and using the serial command protocol, the current is always measured as 0, even after changing the y-axis range on the plot and increasing the current calibration value. I understand from the documentation that the value of the current variable will always be 0 unless a current limit is enabled. I though that simply setting the max current to a non-zero value would suffice. Is there another way of enabling the current limit?


Hello, amr.

Unfortunately, 150mA is a very small current for the jrk to measure and I don’t think you’ll be able to get a good reading of it. The current limit feature is intended for larger motors. What are you trying to do?


Hi David,

I agree, 150mA is quite small compared to the nominal current range of approximately 10A, but I was still expecting to see some activity in the current variable. I’m trying to use it to detect when my motor stalls.


I am trying to measure the motor current with a small motor as well, and get a zero measurement, even when the motor is full on, with no load. I measure about 115 mA with a meter under these circumstances. The motor is driving a propeller in water (with no speed detect), and I wanted to use the current as an indication of how much energy it’s using. When I load up the motor the meter reading lines up with the current variable. Is there any way to set the controller to improve the measurement at the bottom end?

Hello, David.

Sorry for the delay in responding. Unfortunately, I don’t know of any way to make the jrk’s current reading more accurate.