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Author Topic: Transport Control via RS232  (Read 1933 times)
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Step one seems simple, I should setup a pin as an output and write it low.
For step two should I wire Pin 8 directly to digital pin?  If so are there steps that I need to take to protect the arduino from getting fried?
Do not wire the CTS & RTS pins on the 9 pin D-sub connector directly to the arduino pins as this will probably knacker your arduino. The MAX232 board you have has a spare RX/TX pair so you could try and connect relevant wires onto these spare pins so the MAX232 does your TTL/RS232 level conversion needed for the RTS/CTS signals. Another option is to buy another TTL/RS232 converter that breaks out CTS/RTS like this http://www.ebay.co.uk/itm/MAX232-RS232-Serial-To-TTL-Output-Converter-Board-RXD-TXD-RTS-CTS-F-PIC-Atmel-/290712442058?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item43afcfd4ca
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I'm going to double check all the connections but so far the CTS is not going High.

Any thoughts?

Make sure you fully understand how RS232 is connected and the relationship between pin numbers and signals at either side of the connection. Note that the connections are (usually) not made directly between the numbered pins on each connector but are crossed in pairs (txd and rxd are crossed, and so on). You need to follow through the sequence of steps described in that spec, relating it to control signals and hence to specific pins on each side of the connection. I thought it made sense, but I could be wrong. Once you are clear what the sequence means, you should be able to see the signal levels of all pins in the expected state with RTS inactive and then take RTS active and see the CTS become active in response. If that doesn't happen then either there's a hardware problem, or the description in that spec is wrong, or you (and I) have misunderstood it. I don't believe you need to actually send or receive anything over the serial port at this stage - you're testing the signaling preamble that precedes the data transfer.
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Make sure you fully understand how RS232 is connected and the relationship between pin numbers and signals at either side of the connection. Note that the connections are (usually) not made directly between the numbered pins on each connector but are crossed in pairs (txd and rxd are crossed, and so on).

Yup...  Got it...  The manual does say that the cable should be a one to one or a straight through cable.

I don't believe you need to actually send or receive anything over the serial port at this stage - you're testing the signaling preamble that precedes the data transfer.

This makes sense to me.  Make sure that the recorder is looking for data first and then once thats complete move on to bigger and better things!


Do not wire the CTS & RTS pins on the 9 pin D-sub connector directly to the arduino pins as this will probably knacker your arduino. The MAX232 board you have has a spare RX/TX pair so you could try and connect relevant wires onto these spare pins so the MAX232 does your TTL/RS232 level conversion needed for the RTS/CTS signals.

So db9 pin 7 to pin 7 on the chip, and db9 pin 8 to pin 8 on the chip.  Then connect the chip pins 10 and 9 respectively to my arduino?

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So db9 pin 7 to pin 7 on the chip, and db9 pin 8 to pin 8 on the chip.  Then connect the chip pins 10 and 9 respectively to my arduino?
Yes that's right. The MAX232 chips pin 10 will be your arduino RTS and 9 will be CTS. Be aware there logic may be reversed so when the arduino pin connected to RTS is LOW the MAX232 output (pin 7) will be HIGH. Reading CTS will confirm if this is the case.
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I was just trying to get an old  PMD560 at our station automated... I was lucky to find this thread
but I also wanted to use the status sent back from the recorder
did using the second set of max 232 drivers for (CTS or DTS) status work?
now it just records and you never know if it "really" happens 
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