TTL serial communications

Projects Networking, Protocols, and Devices
1

I have a motorized telescope mount that I want to interface with the Arduino Mega 2560.

At first I thought it had a RS232 port, so I bought the appropriate shield. Turns out it actually has TTL communication. For a second, I thought of building a RS232 to TTL converter. Then I realized I could hook one of the Arduino transmit pins to the scope mount's receive pins, hook the Arduino's receive pin to the scope mount's send pins, and tie the grounds together. Is there a flaw to this logic?

How can I be sure the voltage levels are compatible? What about the baud rate?

Thanks in advance!

2

How can I be sure the voltage levels are compatible?

With a multimeter.

What about the baud rate?

RTFM?

3

I so often get a helpful answer here. But...

A multimeter will help me with the powered part of the circuit. But that other end is the part I need to worry about. Obvious.

And thanks for the useless suggestion to R the FM. If there was a manual, I'd have my answer by now.

On the other hand, if you have nothing to add to the conversation, then I understand your four word response.

4

If there was a manual, I'd have my answer by now.

If you don't have a manual, you have no way of knowing what to send to the telescope to start it talking, if it needs to be talked to first. You have no way of knowing what it is telling you. Is it sending ASCII data or binary data? At what baud rate? Using how many start and stop bits? What parity?

Notice that I did not say RTFM! I said RTFM? as a way of determining whether you had such a manual. If you have no idea about what to send to the device to get it talking, if you need to send anything, or what the device is sending. If you are lucky, and the device does not need prompting, then all you will need an oscilloscope and lot of patience to try to understand the bit pattern that it sends. From the scope data, you can determine the baud rate and start and stop bits (maybe). Then, you can start collecting data with the Arduino, and hopefully make some sense of it.