How to physically connect a voltage monitoring meter device(ND20) with RS485 out, to a computer with Modbus RTU? Should I use a converter to RS232 and connect to serial COM port of computer? Should I use RS485 to USB converter to connect? Can I connect directly to serial COM port from A,B and Ground of RS485 using D9 connector pin? Then A,B and Ground to which pins of D9 in Modbus RTU?
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2 Answers
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If your computer doesn't support RS485 protocol, and if we're talking about regular PC's it most probably doesn't, then you cannot directly connect A and B to serial port. I would suggest using an USB-RS485 converter.
answered Nov 6, 2016 at 8:24
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2\$\begingroup\$ Also, speaking only from experience, I would highly suggest avoiding the cheap ($5) converters on Amazon/eBay. Save yourself the headache of not knowing whether or not your converter is the problem or whether the driver installed correctly. Buy a good one ($20-50). \$\endgroup\$ Commented Nov 6, 2016 at 13:42
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1\$\begingroup\$ I agree with this. I even had some situations in which the same converter didn't work for some devices, while it worked for some other devices. \$\endgroup\$ Commented Nov 6, 2016 at 16:01
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\$\begingroup\$ Can you suggest a reliable device? \$\endgroup\$ Commented Jan 10, 2017 at 6:23
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Serial port on almost all IBM compatible PCs is of type RS232. You should check your motherboard's manual. If you MB is from an industrial manufacture (e.g. Advantech or MOXA ) most likely you MB has a RS485 port. And this just the beginning! And then you need some sort of Modbus software that can talk to your device.
