o move, to avoid a collision.
I am designing a system that wil use toe motor controlers. One of the controllers will be separated from my master controller, with two slip rings between them. I need some sort of digital communication through the slip ring. But, I am concerned about noise. The slip ring I have currently chosen is this one with 12 lines;
robotshop.com/en/slip-ring-flange-736.html
Is it viable to connect two separate programmable motor controllers with some sort of serial protocall through this slip-ring. Is there a particular protocal that is native to a programmable controller, that is a good choice? I don’t know which motor controller I will use yet. One I was considering is the RoboteQ SDC2130, which has both RS232 and USB Communications
robotshop.com/en/roboteq-sdc2130.html
Here is the system as I currently envision it;
On Base;
Master Motor Controller, and Radio Controller.
Two motors, each with 5-channel Gray Code Absolute Encoder on output shaft, and Quadrature on the motor.
Through Slip Ring;
4 wires passed through from the radio control.
3 Wires for RS-232 communication.
On End Effector;
Slave Motor Controller.
Two motors, each with 5-channel Gray Code Absolute Encoder on output shaft, and Quadrature on the motor.
Of course, the main issue, is the communication system. Is RS-232 a good communications protocal through the slip ring. Any comments on this, or on the whole system?
-Joe
Hi Joe,
In any communication system where you have possibility of corruption of data (signal noise, for example) or loss of connection (wireless communication, slip ring having a spurious faulty mechanical connection, etc), you should always use a communication protocol that includes at the very least a way to detect errors.
The easiest way to do so would be to frame your messages with an identifiable start/end and add a basic checksum (for error detection) to confirm the data is good. More advanced communication protocol may also add error correction systems.
A very secure approach would be to have a small microcontroller on each point of the communication performing error detection and decoding/encoding of the data to ensure its integrity. This may not be always practical or feasible (size, power and/or cost constraints), but does make for a very secure communication. We recommend that you read the manual of your intended motor controllers to determine if their serial communication protocol offers error detection (and maybe even correction) and if it does, what happens when wrong data is sent (does it simply ignore it, does it notify the sender, etc.). You may have many unknowns at this point to we recommend that you try and obtain as much information as possible about your various components and how they communicate.
Sincerely,