Uno to serial port (not USB)

I would like to have my Uno talk to and control a device which communicates via a serial port only. Can I just connect pins 0 and 1 to the TX and RX ports of the device's serial port, as well as power and ground and call it good? Does the additional pins on the receiving serial plug (CD, DTR, DSR, RTS, CTS and RI) need to be dealt with in any way or can I just ignore it? Once its all wired up, will calls to Serial.print simply send the data down via pins 0 and 1?

Thanks, Peter

pbako: I would like to have my Uno talk to and control a device which communicates via a serial port only. Can I just connect pins 0 and 1 to the TX and RX ports of the device's serial port, as well as power and ground and call it good? Does the additional pins on the receiving serial plug (CD, DTR, DSR, RTS, CTS and RI) need to be dealt with in any way or can I just ignore it? Once its all wired up, will calls to Serial.print simply send the data down via pins 0 and 1?

Thanks, Peter

First you have to determine if the external 'device' uses true RS-232 serial voltages or TTL serial voltages, only the latter can be directly wired to arduino pins 0 and 1, while the former will damage the arduino. If the device is using RS-232 voltages then you will have to build or buy a RS-232 to TTL converter module which converts the voltage and performs a logic inverstion for the two signal lines send and receive, something like this is one example: http://www.sparkfun.com/products/133

As far at the serial control signals (CD, DTR, DSR, RTS, CTS and RI) the Arduino does nothing with them nor requires any of them as inputs. You will have to determine if your external 'device' requires any and make provisions. Often this can be accomplised (if required) by just jumpering pins together in the DP-9 connector such as RTS to CTS, etc.

So what you need is more details about the external 'device' and it's requirements.

Lefty

Thanks for information. My destination device is a serial controlled relay box (http://www.electronickits.com/kit/complete/elec/ck1610.htm), that I bought a few years ago for another project that never worked out. While getting ready to measure the Serial voltages, I found a serial shield from CuteDigi (http://www.cutedigi.com/product_info.php?cPath=284&products_id=4329) and decided to just use that.

Peter

pbako: Thanks for information. My destination device is a serial controlled relay box (http://www.electronickits.com/kit/complete/elec/ck1610.htm), that I bought a few years ago for another project that never worked out. While getting ready to measure the Serial voltages, I found a serial shield from CuteDigi (http://www.cutedigi.com/product_info.php?cPath=284&products_id=4329) and decided to just use that.

Peter

That should work. However it does appear that both the controller device and the RS-232 shield are both wired to be DTE devices. What that means is that the DB-9 cable connecting these two pieces together need to have pin 2 at one end wired to pin 3 at the other end and pin 3 at one end wired to pin 2 at the other end. Otherwise known as requiring a null modem connection.

http://en.wikipedia.org/wiki/Null_modem

Lefty