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Author Topic: RS232 doesn't work with certain device  (Read 2578 times)
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If the information you provided is correct, it should give around +/-13V as the standard assumes. How do you get +/-7.5V? The MAX3232 is able to push the 5V input up to over 13V for up to 120kBaud, the supplied schematics connect the MAX3232 as the datasheet proposes so you should get a correct voltage level.
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Ok, then I misread something smiley-wink

It's really strange why it doesn't work.
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Hi

I see that there aren't pins on the RS232 connector connected. (propably because the module has external RTS/CTS)

What pins should I connect? In the arduino softwareserial I have found the pins, but they are wrong.
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Earlier you wrote there is no handshake at all. Why are you concerned now about RTS/CTS?

SoftwareSerial has no hardware handshake, so what pins are you referring to?
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The manual says no handshake, but maybe the RTS and CTS pins should be constant high/low for the video mixer to read out.

I don't use softwareserial, but real serial (TX/RX). The softwareserial tutorial just shows how to connect the MAX3232 (that says to connect pin 7 and 8, and TX to 7 and RX to 8???)
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If no hardware handshake is used, RTS and CTS should not be relevant at all. But the mixer might look for the DTR signal to check if a controlling device is connected.

Maybe it's time that you show us the whole wiring of your project as you have it currently. Is it possible that you take a photo or draw a wiring diagram?
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http://www.mediafire.com/?r5zrnal6caz9d

These are some photos from the wiring. Nothing special, just TX/RX to the TTL to RS232 board and 5V to it. Then the fader is 3.3V power/ground and the other wire to A0 input.
Hmm, I just see that the shadow doesn't let you see anything. The blue wire is connected to TX and white to RX

How can I use the RTS and CTS port? Should I just connect it with a digital port and send High? Or how does it works. It's plausible that the video mixer sees if a device is connected with the RTS/CTS.
Or should I connect certain pins from the connector?

Thanks for the help! I'm a really newbie in serial/RS232/arduino/IC stuff smiley
« Last Edit: June 02, 2012, 09:27:55 am by alfaleader » Logged

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I am a little puzzled, to say the least, that you don't seem to have anything connected to the output of the RS232 board. How does that work?
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The output of the RS232 board is connected with a standard RS232 cable to the video mixer.

The TTL to RS232 is connected to the arduino with the blue/white cable to TX/RX.

Is it possible to connect a digital port from the arduino to the CTS (clear to send) from the TTL to RS232 port? And just write high to this port so the MAX2323 sends over RS232 that there is a device connected.
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Just tie it high (or low as appropriate) - you don't need to write to a pin to do that.
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