I’m trying to control two bipolar stepper motors with a single Tic834 controller, wired like this:
(the two motors drive wheels on a robot that are on the same virtual axis.) My stepper motors require 600mA per phase. Given that the power source is sufficiently strong, how do I set the Tic settings? Shall I choose 1200mA as the current limit? What else must I take into consideration?
(It seems that if I set the current limit above 700mA, some error occurs and I don’t know yet why.)
You can connect two stepper motors to your Tic in parallel as you described as long as you do not require independent control of them. In this case, you should set the current limit to twice the rated current of your stepper motors, but be careful that you do not accidentally energize the driver with just one stepper motor connected.
What error are you encountering when you raise the current limit above 700 mA? What feedback do you receive from the Tic Control Center? If you have not already, you might check out the “Error handling” section of the Tic user’s guide to try to get a better understanding of what is going on.
thank you for the quick response. In case I set the current limit to 1200 mA (or even 900 mA) the motor is driven for ~0.5 s, then comes a “Motor de-energized because of motor driver error.” message. And this repeats: half second of driving, half second pausing. (But the axis not moving. Safe start disabled.)
I think I have found (at least one) source of the problem: I drive the motors from a big power bank with 5V and 2.1A max. output. Even though the motors require only 3.9V, under heavy load the voltage of the power bank drops significantly and it becomes too low for two motors. It seems I need one power bank per motor or another, stronger power source.
I’ve tried again with 8x1.2V NiMH batteries and better wires. The motors require 6V and 600mA each.
According to my measurements the voltage and current are okay (10V & 1200mA) up to a speed of ca. 2500 steps/s, and from there the current drops quickly to 300-400mA, and with a little increment of the speed at least one of the motors stops.
With the power bank the same thing happens but not at around 2500 steps/s but already at around 2000 steps/s.
Do you have any suggestions?
This forum thread has some general tips for maximizing the speed of a stepper motor, so I recommend taking a look at that.