Hello,
I can’t understand from the MDC30C manual how to hook up switches to reverse direction. All it has it a picture showing two limit switches soldered to the board. What do they do?
While we’re at it, what does the EXT POT do? That is, does low R correspond to motor on or off? I have an eBay controller that when the POT is disconnected (input hi R), the motor runs! This is a bad plan for my go kart: if a connection fails, the motor turns on by itself.
THanks,
Cosmotion
MD30CUsersManual (1) Robot Shop Motor Controller.pdf (1.92 MB)
Before going into any details, can you indicate what it is you’d like to provide as an input? If you just want a switch, or if you plan to use a knob / potentiometer? Do you want to have the output be variable speed and if so, how? The more info you provide, the better we can help. Note that the MD30C accepts PWM input.
Thanks for the fast reply!
I plan to use a 0-5KOhm foot pedal for the speed control input. So the output will be variable speed. This is for a gokart.
I would like to use a rocker switch to control the direction.
You would therefore need a DC motor controller which accepts -5V analog input, not one which accepts PWM. A foot pedal cannot provide a PWM output signal, so if you still want to use that, you’ll need a microcontroller to read the analog voltage, then convert it to a PWM signal. This would require programming and no sample code for this is provided. If you are not comfortable programming, you might want to change the controller.
The board has PWM, so i don’t need PWM input. The speed is externally adjustable with a 5K pot. This seems clear in the manual, p. 13:
"External Switches and Potentiometer
Set the jumpers as below:
JP4 :EXT POT
JP6 :INT PWM
Connect the external switches and potentiometer as below."
The pictures on p. 14 show two limit switches connected to JP8 and JP7. Can you please explain their function?
We apologize, an you are correct; although the primary input is PWM, the board does accept analog input.
You first need to change the PWM source (page 6 in the guide) to EXT POT.
Follow step 5: “Connect to the external potentiometer (5K 10K Ohm). Used to control the motor speed when PWM source is external potentiometer.”
Note that you need to solder pins or wires to the board.
The buttons labeled 7 and 8 control the direction of the motor. You can de-solder the buttons to hook ones up further away, though this would void the warranty, and there is no guarantee that a replacement button would work.
Thanks, Benson.
The switches are clearly labeled S1 and S2, not 7 and 8. There is clearly no need to desolder the switches, as that is what jumpers 7 and 8 are for.
But what i need is a DESCRIPTION OF THE FUNCTION OF THE SWITCHES. I don’t want to have to guess, as it might not be what i need. If i were to guess, it seems that on intermittent closure of either switch changes the motor direction, is that right? That is still not enough information, since intermittent switch systems like this have hysteresis (that is: the motor can be going in either direction and the switches are both open). So you have to have a way to set the motor direction at the beginning. Otherwise, you turn on the system, and it could be going either way.
Can you please ask someone who has really worked with this board?
The onboard functionality allows you to use either the onboard potentiometer to vary the speed, or to connect an external potentiometer, while the buttons activate the motor (direction).
Correct. You use the two buttons on the board to power the motor; one button rotates the motor in one direction, while the other rotates it in the opposite direction.
The board is too simple for that. The way you connect the motor leads to the motor terminals will also affect direction.
If this does not clarify the functionality of the board, the manufacturer can be contacted here: cytron.com.my/support.php
