Addressing SSC32 with multiple other boards on RS485

Lynxmotion Electronics & Software
1

Hello all, I’ve been reading this board with great interest…have not seen this topic covered elsewhere.

I have an SSC32 board connected on COM1 port of a computer, in a daisy-chain configuration with 6 other stepper motor controllers. For various reasons it’s most convenient to use a single com port to control all of them from the application software.

Anyway, the 6 stepper motor controllers (provided by allmotion) can be addressed separately because their command structure allows a board address for commands. So I can send the string /1 A1000 which tells board 1 to move the moter so many steps, etc. All the other boards (boards addressed 2-6) know that they should ignore this command because it’s not addressed to them.

If I send a command string to the SSC32 board, no problem, the stepper motor boards will ignore it because they expect to see all commands prefaced by the / symbol and will ignore anything otherwise.

But how do I prevent the SSC from reacting to portions of the stepper motor commands? There may be all kinds of letters (Q, VA, etc) in the stepper motor command strings and I’m afraid the SSC will see those characters on the serial line and think they are commands to be acted on.

Thanks for any help!

2

As far as I’m aware there isnt a specific way of doing it. Move commands are prefixed by # and must end with carriage return. If it recognises part of the command it may act on it…

Depending on how you are implementing your link, it may be possible to gate your data using RTS (dependent on what control you have on the ports).

We did a system that had an Octal acdressing system and we needed to double the number so the one set was AND’ed against the Data the other was NAND’ed if I remember right.

With RTS high one st received data, with RTS low the others did. Its a long winded way of doing it though

3

Thanks… I might have to re-code for multiple serial ports. I was hoping that there might be some simple firmware modification that could add a character, without which the SSC32 ignores the command.

4

If I remember rightly the firmware code is open source so you could go down that route but it would be at your risk…