SSC 32 and DC Motors with Encoder

Help & Support Robot Parts
1

Hello,

I need to find a way to control the dc motors (with or without encoders) from my Skywatcher (Acuter, Celestron) Merlin Head
( ca.skywatcher.com/upfiles/en_dow … 042331.PDF) with my Lynxmotion SSC 32.

I know, that the Lynxmotion Controller is intended for another kind of Servos.
Is there, even in theory a kind of device or hacking method to let the SSC 32 communicate with the Merlin Head?

Since this would be very important for my planned setup I would really appreciate an hint or help!
Thank you very much in advance!

All the best,

Hans

2

Welcome to the forums!

As a general rule, any of the R/C motor controllers can be used with the SSC-32 board:

If you want to use encoders to give some speed control, we would recommend considering one of the JRK motor controllers:

We hope this helps.

3

Thank you, Jeffrey! Do you mean, I have to bypass the built in i.r. encoders the merlin head uses an connect the motor directly, as “regular” dc motors? So I would loose the merlins ability to “know” its position on the axis and just be able to control speed and running time of the motor? Thank you in advance and sorry for my noob questions. Kind regards, hans

4

I may be missing something here, but from your link, it appears like you control the Merlin head using RS232 (serial) communications. If that is the case the SSC-32 could not do anything to control it. You can control it directly from your PC or from other General Purpose micro-controllers like the Arduino…

5

Hello Kurte, yes normally these heads are controlled using serial communication. I was wondering, if there was a way to skip their protocol and respective electronics and talk to the heads using the ssc32 and somehow treat the built in dc motors and their encoders as servos. I mean modifying the heads and just connect the motors. The reason is, I already have a working setup using the ssc 32 and the dedicated sequencer software. For a project I wanted to control the merlin heads in my existing setup, using the same software. I guess I was wrong, since these kind of motors with encoders don´t act as “regular” servos. Am I right? Sorry for my stupid questions. I am not very experienced in this kind of devices. Thanks a lot for hints and comments! All the best, Hans!

6

My guess is it would take a lot of experimenting to find out what the motors are, likewise the encoders find the specs for them. Also find out what processor is on the board and if someone (hopefully the manufacturer) has made it such that you can flash new software and have sources available… Then you might be able to add/use some IO pins, that can read Pulse widths to control the motors… (Or replace the whole processor…) In theory you could then use the SSC-32 to generate the pulses, but if then wanted feedback from the encoders to where it actually is, not the SSC-32 is not really setup to do that.

Alternative, get some simple processor like an Arduino or Teensy or… Use a couple of it’s IO pins and create servo extension wires that connect up to the SSC-32. You can then have a program on that processor, which receives the pulses from the SSC-32 and then generate Serial commands to output to the Merlin head…

7

Kurt’s approach would be the best if you want to minimize the modifications to your Skywatcher.

8

Thank you very much for your help guys!