Dual Serial Motor Controller Serial Interface

I’ve just bought two of these guys, and I’m a bit disappointed. I thought that what I was buying was a ready made solution to plug into a PC, I even skimmed the online docs before buying and noticed a DB9 serial plug as part of the schematics…

Instead it’s 5V tty levels.

My project is using a mini-itx motherboard, and I’m wanting to use both controllers on one serial line. So I guess my question is

  1. I’ve got fir/sir data transmit available on the board, (I’m using Linux) have you ever heard of anyone using these to control tty level serial?

  2. When having both controllers setup, the serial line is attached in parallel right? any special concerns about this that you’ve run into?


I’m sorry you’re disappointed, but I don’t see where we come close to claiming that the micro motor controller connects directly to a PC serial port. We have a picture of the unit, which clearly doesn’t have a DB9 connector, we say that the input is for logic levels, we have multiple non-PC sample projects, and we specifically show a circuit for connecting to a PC serial port. Is there something misleading that I missed? (Your statement makes it seem like you’re blaming us for your not looking beyond one component in a 4-component diagram.)

  1. I don’t know about the fir/sir lines you’re talking about, but I suspect they’re IrDA-specific. If there is some straight UART-type connection to an IrDA modulator that you can tap into, that might be more promising. If the lines you are talking about are meant to connect directly to an IR LED, it’s very unlikely that would work with our motor controller.

  2. Yes, your serial lines would be in parallel, though it’s usually not referred to that way. As you connect more items to the line, you might call it a bus, and another common term is “daisy chaining” when you connect multiple points in a chain (as opposed to splitting of from one central point). It should be fairly straightforward as long as your wires don’t get too long, which is a problem even without multiple units on one serial line.

By the way, I don’t see how your questions are related to this thread; in general, please start new threads for new questions.

- Jan

From your ad

I doubt it was intentionally misleading, but to me computer with a serial port means an RS-232 serial port that is on the back of the computer. I looked into it further and saw a circuit diagram showing a db9 connector and assumed that circuit was part of the kit, although it wasn’t shown.

Be that as it may, I’m willing to work with what I have. I have a Mini-ITX motherboard that’s I want to use in a robot. http://www.via.com.tw/en/products/mainboards/downloads.jsp?motherboard_id=21 The FIR/SIR lines I’m talking about are IrDA-specific. (page 30 of the manual) are described as
Pin Signal Description
1 +3V VCC
2 IRRX FIR/SIR Data Receive
3 IRRX2 SIR data Receive
4 Grd Ground
5 IRTX FIR/SIR Data transmit

I think I’m going to have to wire together the db9 circuit.

Sorry about posting to this thread, I thought the title was the dual serial motor controllers. Feel free to move it to a different topic, as moderator you should be able to. I don’t think I can.

Yeah, I see now; I changed that text to make it more clear. I was originally looking at the micro version since that was the thread name; is that not what you have?

- Jan

I’ve got two of these guys.

I thought they were the micro ones. I see the confusion. There are more micro ones available :0

I’ve changed the subject to avoid further confusion.