Use the simple way below to confirm: Measure Pin 3 and Pin 5 of a DB-9 Connector with a Volt Meter, if you get a voltage of -3V to -15V, then it is a DTE device. A modem is a DCE.ĭTE normally comes with a Male Connector, while DCE comes with a Female Connector. DCE stands for Data Communication Equipment. DTE and DCEĭTE stands for Data Terminal Equipment. RS-232C, EIA RS-232, or simply RS-232, refers to the same standard defined by the Electronic Industries Association in 1969 for serial communication. Step 1: Understand RS232 Connection & Signals If you have a chance to test your RS232 devices with the 232Analyzer software, you should be able to control your RS232 devices in a short period of time. On the transmit side you just go through the inverter and hope that the device you are talking to can register logic level voltages - many can, though it's not guaranteed to work.This article will explain the following topics in details:ġ) Step 1: Understand RS232 Connection and Signalsģ) Step 3: Control your RS232 devices by using 232AnalyzerĪfter reading this page, you should be able to understand most of the hardware and software (protocol) standards for RS232. You may at low baud rates be able to receive RS232 using a resistive voltage divider feeding into an ordinary 74whatever04 inverter. You can get a USB-serial converter to let your PC talk directly to the receiver or to the RS232 arduino for about $12 many places.įinally, in the "not officially recommended category" if you want to play with it today, you could look at hack solutions to accommodate the dual needs of level translation and logical inversion between a bare microcontroller such as on the arduino and the RS232 standard. I still think the cleanest implementation would be to to find or re-create an older arduino board that has the 9-pin connector and level shifters built in instead of the USB interface of recent boards, and upgrade it to an atmega328. If you want to buy a bare chip and wire it up with the caps yourself, they publish schematics. I'm not seeing one here on the adafruit site (apologies if there is one I missed) but sparkfun has several to chose from. Your simplest option is probably to buy an RS232 level shifter kit/board. If you write portable code and periodically compile for the arduino during your PC-based experiments, you'll become aware if you start coding in a direction the little chip can't support. Then when you have the basic idea of how it needs to work, you can port it to the arduino. Generally, for software projects where the hardware component is something standard like serial, it's often wise to first write the code on a PC (but as if it were an embedded system with limited libraries) and get it talking to the device under control. Actually, if you could find an older-generation arduino with the 9-pin connector on it instead of USB and just change out the chip for a recent atmega328, you'd have a more integrated solution than using your uno + a level translator. Usually something based on the MAX232 or one of its many descendents is used, since that can generte the +/-12v using onboard charge pumps instead of needing external power supplies as the old 1488/1489 did. If I can get some help setting up the connection I will be thankfulĮlectrically it sounds like you will need a level translator to go between the logic level serial of the Arduino and the standard RS232 levels of the device you want to control (the signals are also inverted in the process of level translation). Synchronous system : Tone step synchronizationĬommunication system : A half duplex Communication speed : 9600bpsĬommunication data length : 135 bytes (maximum) RS-232C Connector type: DB-9pin female type, slave straight connection (DCE type) ( 1pin : GND, 2pin : TxD, 3pin : RxD, 5pin : Common(GND), 4,6,7,8,9pin : NC ) My main problem is to make the proper RS232C connection. I found a pdf describing the protocol on the internet: The project I want to do is making the Arduino control my Denon AVR-2808 surround receiver which has a RS232C interface. I recently bought an Arduino UNO to play with. I'm a newbie when it comes to electronics, but have many years experience with programming.
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