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Htguru

90 30 CPU350 serial connection

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ok running into a issue here, so we were able to communicate with the processor to download a program. transfer went fine. upon cycling power, we can no longer connect to processor. we used LM90 for the software. i've tried removing the battery and shorting out the "mem clear" points on the board, however we can no longer communicate with the CPU. we have a POWER and OK light solid on the power supply. kinda stumped here if anyone has any insight.

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Default serial port settings, to which it should have reverted when you removed the battery and shorted the capacitor, are 19200 baud, 8 data bits 1 stop bit, odd parity.

What are you using for a cable and RS485/RS232 converter? The converter gets its power from the port. Pin 5 is +5 VDC, pin 7 is GND.

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Posted (edited)

No converter, I have a serial port build into laptop, so a straight cable from PC to power supply. Port settings are as you described

 

Edited by Htguru
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The port on the power supply is RS485. I've never seen a laptop with anything other than RS232. RussB posted a pin chart for a "cheater" cable that usually (but not always) works. You can search the posts for it. Is that what you're using? RS485 is a differential signal and more immune to noise than RS232.

Another thing to check is to make sure no other application is using the serial port. RSLinx used to be notorious for not relinquishing the serial port even when RSLogix wasn't running.

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Yes, sorry should have specified it's a rs232 to rs485 cable. I will check on rslinks using the port, thanks!

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