RS- 2. 32 Connections That WORK! This FAQ will help you troubleshoot and correct such problems. Usually inputs are connected to inputs and outputs to outputs. People don't realize that there are two types of RS- 2. DTE and DCE type, and that the signal names and pin numbers are the same, but signal flow is opposite! The pin labeled Tx can be input, and Rx the output. The two ports types are complementary, the Output signals on a DTE port are Inputs to a DCE port, and Output signals on a DCE port are Inputs to a DTE port. The signal names match each other and connect pin for pin. Signal flow is in the direction of the arrows. Think COMPUTER for DTE. What devices have DCE type RS- 2. Think MODEM for DCE. Rule of Thumb: When connecting a DTE device to a DCE device, match the signal names. When connecting two DTE or two DCE devices together, use a Crossover cable. Serial Data Converters Power supply Supply voltage. Serial interfaces are used in most electronic equipment today. Some of the original serial interfaces like RS-232 and RS-485 are still widely used.Are My Devices Wired As DTE or DCE? If the device connects to the computer port using a . The tester can show the signal state of any active RS- 2. LED's lighting Red or Green. Active data lines are output from a device, they may be either High or Low. Just plug the tester into either of the two devices, see which lines are lit, unplug it, then plug it in to the other device, see which lines are lit. If not, try swapping the leads with a null modem cable, see if the other LED now lights. If not, you may not have enough voltage on the handshaking lines of the port to steal power from. Use a DC Voltmeter - Technicians with a DC voltmeter can use it to measure the DC level from signal ground (pin#5 on DB9, pin#7 on DB2. When the unit is powered and not sending data, the output line will have a DC voltage of minus polarity, 3 volts to 1. The other pin will have little or no voltage. For example, we measure - 1. DB9 connector and the line is labeled RD or Rx, then the device is wired as DCE. If we measure the voltage on pin#3, it is DTE. Measure pin #2 and pin #3 to ground (pin # 5 - DB9) (pin #7 - - DB2. If the cable and device have voltage on the same pin, you need to use a crossover or null modem connector that swaps pins #2 & #3 and the other pins. Active handshaking lines can be found by measuring each pin for voltage. Generally about wireless serial RS232 connectivity. Connecting a wireless serial RS232 device to a computer can be quite complicated if you don't know where to start. This article tells you just about everything you need to know to get a RS232 connection working between. Download the free ComDebug serial port monitor software. The ATEN USB-to-Serial RS-232 Hub provides an external plug-and-play RS-232 serial connection for computers, notebooks, laptops, and handheld computing devices that. Serial Communications 101. This technical white paper describes everything you'll need to know about RS232, com ports and serial communications. Output lines will have voltage. On a DTE, DTR and RTS will have voltage if used. On a DCE, DSR and CTS will have voltage, and if a modem with CD (Carrier Detect) and RI (Ring Indicator) these last two will be low until Ring is detected or a Carrier connection is made. If handshaking lines don't have voltage when the device is powered on and ready, the device doesn't output them, they may be looped back, RTS to CTS and DTR to DSR. You can turn off the device power and measure for continuity (zero ohms) between pins to confirm if they are looped back. Other RS- 2. 32 Connection Problems. Handshaking lines RTS and CTS not interconnected, DTR and DSR not interconnected. Swap as needed. Programs may use the RTS/CTS connection to check that a device is ready to receive data and respond. If there is No CTS connection, the program will never send data, but wait a long time or timeout with an error. The RTS line may need to be looped back to the CTS input. Data errors can occur if the device actually requires handshaking. Programs may also use the DTR/DSR line connection to check that a cable is connected or that the device is turned on. If there is No DSR signal, the DTR line may need to be looped back to the DSR input. Some devices use DTR handshaking. Each signal required for unit operation must be carried through by the isolator, modem or RS- 4. There are 2 data flow control channels, RTS and CTS. If these are missing, data is lost, characters missing, or files scrambled. Connections to Telephone Modem/FAX modem - Make sure CD & RI lines are connected.
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