Internet PLC Forum
General => Technical support => Topic started by: wakko59 on June 20, 2007, 10:59:01 AM
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Hi there,
Brand new to this. I have a T100MD-888+ and get the message
(Warning: No Response from PLC !) when I try to send the IR* string in the Serial Commd Setup screen. Ive set the PC port to match the Baud rate and Comm1, parity,stop etc but get no other message. Get an error if I try to Detect PLCID. I have a Switch mode PSU connected at 24v (ATX unit for a PC). I dont think I have any other software which is using the RS232 port.
Tried just transferring a sample program also doesn't connect
Any help gratefully recieved. Wakko
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Are you running TLServer to connect to the PLC? The default settings after installation of TLServer and TRiLOGI software is 38,400, 8 data bit, 1 stop bit, no parity and you shouldn't need to change it. However, it is likely that you are not using the correct com port number. Does your PC has a built-in COM port? If so, then the COM port number is typically COM1 or COM2. But if it is a USB to RS232 converter then the COM port could be COM4,5,6,7 etc. Please try a different COM port number to see if you can get it to work.
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Thanks for the Reply,
Yes All port settings are the same for both PC and PLC. I have the TL server running and I am using the RS 232 port (not the USB port). Disconnecting the serial cable from the PLC board and trying to connect gives the same result ( Warning no response....) It's as if the PLC board is not connected at all.
I am currently checking that all is well with my PC port and this points to a faulty board no??
Is there any other test I can do? Is there an issue with SwitchMode PSU's?
Thanks again
Wakko.
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Switching PSU should be OK if it is not giving out excessive switching noise and has regulated output power.
When you turn on power to the PLC, did you observe that the 3 status LEDs (RTC.Err, Pause, RunError) all lights up for about 1 second and then goes off? If so, it signals that the PLC is properly powered up and will run the internal program.
When the PLC is shipped from the factory there is a sample clock program loaded and if you have any LCD display or HMI you will see the message on the LCD screen with a ticking clock. That will indicate that the PLC is functioning.
You may also want to try to install the TRilOGI software in another PC and try with TLServer again just to be sure that it is not a problem with the serial port on your PC.
If all else fail, please contact support@tri-plc.com directly to see if there is a need to request for RMA for repair or replacement of the PLC.
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Thanks again for your help.
The PSU is a brand new ATX Computer PSU so I expect is is well regulated.
Yes the LEDS light up and extinguish as described leaving the RTC LED on
The ticking clock is also working
I ran a Loopback test on the PC by shorting together
RX-TX, DSR-DTR, and RTS-CTS pairs and opened up a session in Hyperterminal and typed in some text which is immediately returned. I assume this confirms a working RS232port.
I have emailed support and described thes details.
Thanks again for your help
Kind regards,
Wakko
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Just a quick question, You say you use a computer power supply
at 24vdc, Are you sure it's not 12Vdc and you need to set the 12/24 Vdc jumper?
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Thanks for the reply,
No the ATX PSU from most Computers has both a +12 and -12V supply which gives a 24 V supply as both are referred to 0V. An interessting article on how to convert an ATX into very stable Bench Power supply at :
(http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply) ... cheap... even buying a New ATX PSU. I'm current investigating the rs232 cable to see if there is an issue with the handshaking pairs.
Thanks again,
Wakko59
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You are probably shorting the -12 volt output without being aware. 0 volt from the power supply is connected to ground. Ground line to your pc plus ground line in your RS232 cable will do the rest. The -12 regulator in your power supply may be a little hot ...
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wakko59 has subsequently informed us that the ATX power supply he used to power the PLC was the culprit. After changing the power supply to an industrial switching power supply the PLC works flawlessly.