This is my first visit here and my first attempt with this kind of stuff. I bought a Serial 8 servo controller to control two Hitec HS 785 HB sail winch servos that will be part of a variable masking system on my front projection screen. The mini SSC II mode works but is not good for the application because the speed is not adjustable. The servos are 4 full turn servos instead of the usual 180 degree ones. I will need full throw so I understand that 8 bit commands are required. I would like 5 second transition time for smooth quiet operation. My Crestron system can send the serial string out via a designated RS232 port but I’m having trouble following the supplied instructions to write the “Pololu mode” string. It would be a great help to me if someone could give me a example of what a complete string would look like if I wanted servo 7 to go to position 254 and take 5 seconds to transition to it.
Each of the two servo’s will have only 4-5 positions required of them so the only variable in the string are servo number and position. Thanks,
You should probably use the absolute position command. You’ll first need to send a speed setting to each servo, and after that, all you need to do is send position commands (unless you want to change speed). There is some additional explanation of our protocol in the document describing using our servo controllers with the BASIC Stamp 2.
Thank you for your reply but I’m still not getting it. I am trying to test this with the “Pololu Serial transmitter”. Using that with the “Mini SSC II mode” I can make the servo’s go to whatever position I want. When I try to do it with the Pololu mode I get nothing. This is what I’m doing. In the serial transmitter, I enter the following in the 5 bite command.[128,1,3,7,1] then select send. I get nothing. The yellow led goes out, I see activity on the green led but no movement from #7 servo. The Mini SSC II jumper is removed. I am un-clear about the “reset” I pulled that jumper and moved it over to the outer two pins then removed it completely. What am I doing wrong. I’ll bet it’s something stupid I’m good at that Thanks,
What you are sending isn’t a valid command. You need to add the second byte for command 3, or you should change to command 2.
Thank you. I am making progress but have run into a bit of a snag. Question, can the serial 8 controller process 2 commands sent at exactly the same time? For instance, my program is telling servo’s 7 and 8 to go to different positions at exactly the same time. Can I do that or do I need to put a small delay between the two? Thanks,
You can’t send two things at “exactly the same time” on one serial line. You’ll have to send one command after the other, and the servo controller can handle them as quickly as you can send them.