I am a user of a JRK in position servo mode using a pot for feedback. It mentions in the user manual that the JRKs are useable as closed loop motor speed controllers with either DC or tachometer type feedback. What input do I use for the tach signal? What means are there for control of the motor speed? I want to use an Arduino output to control the motor speed. Ideally the JRK would accept this signal. The second choice would be a analog signal developed from one of the Arduino PWM outputs.
I am not entirely sure I know what it is you are asking about. It sounds like you were previously using the jrk in a system with potentiometer feedback for position control, but now you want to use the jrk to make a system to control speed with tachometer feedback.
To use the jrk for speed control, you would use the FB pin and supply it with the digital output from an encoder or some other device that provides frequency feedback. If you want to control the jrk with an Arduino, you can use the Arduino’s serial interface. More information about the jrk’s serial interface and feedback can be found inside the “Using the Serial Interface” and “Feedback Options” sections of the jrk’s user’s guide, which can be found under the Resources tab of its product page. For example, here is the jrk 21v3’s Resource tab.