Some RS232 ports (or USB adapters) require signals such as Carrier Detect (DCD) and DCE Ready (DSR) to be asserted before they will function properly. If you want to use a USB UART Adapters on Windows IoT Core, you should know that not only CP2102 USB 2.0 to TTL Module Serial Converter is supported which we can see in the hardware compatibility list, but FTDI and generic usbser.sys devices are also supported. To check whether or not an RS-232 serial port is working, perform an RS-232 loopback test by doing the following: If your serial port is not female, convert it by taking a female/female cable or gender changer and plugging it into the serial port. Take a metal paperclip or wire and cross pins 2 and 3.
You basically short pins 2&3 on the serial port connection then pull up hyperterm, tell it to use the port and anything you type should show up on the screen.That covers the transmit and receive. There are also some handshake issues but if R/W is good you will at least be at a starting point.Pins 2&3 are on the 5 pin row, middle (3) and the one to the right of it.Using hyperterm you might be able to get a response back from the card reader if you type in any of the control codes it uses.The suggestion to use a serial mouse is good, if you have one.Ed FairGive the wrong symptoms, get the wrong solutions. RE: How yo check if Serial Port ( COM 1) working (TechnicalUser). Today I connected my card reader to COM2 hopping if COM 1 is faulty – COM 2 should be O.K.At the beginning all looks fine, led didn't light, but after start Card reading on COM 2, received message 'Error.Also try with other Card Reader – same result.All this bring me to conclusion my Serial Card two ports is gone.Only one thing what I would like to define is to precise what caused this – hardware mater or software- something related to Windows XP SP3.RE: How yo check if Serial Port ( COM 1) working (MIS) 25 Jul 11 14:39.
When you run hyperterm the connected at the bottom left only indicates that there is a com port recognized, it has nothing to do with anything possibly connected on the other side of the chip.Hyperterm takes keyboard input and puts it out to the com port and takes stuff off the com port and puts it on the display.It is probable that you got no display on the screen when you shorted 2&3 because the flow control setting was set to hardware and you didn't have the handshake lines connected. On the test setup it required 4&5 (25 pin connector) to work in hardware handshake but 2&3 worked without the 4/5 jumper while in Xon/Xoff or none.the test setup:DELL GX270 COM1:modem cable 25p-25p gender changer null adapter 232 patch2&3 shorted on the patch adapter, no other wires insertedHT set for com1: 2400 N81 no handshakeIf you have access to a VOM it might be worth a few minutes to ohm out the end to end connections to insure you are dealing with a null cable with minimal handshaking available.Ed FairGive the wrong symptoms, get the wrong solutions. RE: How yo check if Serial Port ( COM 1) working (TechnicalUser). I was using a 9 to 25 modem cable but 2&3 fit for 9 pin cables too.There would be a different set of pins for handshaking but doesn't matter with none.There is a piece of test equipment, a signal level telltale, that lights up LEDs when the signal levels are right. You could also use a VOM to test the voltage on the Tx signal, pin 3 on a 9 pin connector, looking for -12 w/respect to pin 5. The signals coming out of the UART are 0 & 5 but then go through a conversion to +/- 12v in a line driver. Low voltage coming out of the driver causes the receiver on the other end to not flip as there is a dead zone generally +/-3v.Working with 232 can be frustrating, as you now know.If the com ports were disabled in the BIOS you would not have the connected in HT.On modern boards the com ports and the line driver/line receivers are built into a do-everything chip.
Other than turning off the chips in the BIOS and installing a dual serial card in an ISA slot there isn't much you can do. And there is a good possibility you don't have ISA slots.Ed FairGive the wrong symptoms, get the wrong solutions. RE: How yo check if Serial Port ( COM 1) working (TechnicalUser). If there is no voltage on TX, the line drive is dead, done, gone. Double check by measuring on 2. Null cables switch wires. If perhaps we got mixed up in what you are using it may be that you don't have a null cable.
On a 25 cable 2 is Tx. On a 9 cable 3 is Tx.
A null cable on 9 pin port leads to Tx on 2 at the end of the cable.It is designed for -12 or +12 independent of any setting of the UART.The serial mouse is a good idea. Thought maybe it had been suggested before. XP sets mine up at 9600.Ed FairGive the wrong symptoms, get the wrong solutions. RE: How yo check if Serial Port ( COM 1) working (TechnicalUser).