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RS485 to Labjack

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Rich
Richard@EVUS's picture
RS485 to Labjack

Are there any recommendations to connect a RS485 device/meter to a labjack? Is this possible and which input could I use?

LabJack Support
LabJack Support's picture
RS485 is similar to RS232 but

RS485 is similar to RS232 but the electrical specs of the signals is different, so rather than using a MAX233 you need a chip designed for RS485:

https://labjack.com/support/datasheets/t7/digital-io/asynchronous-serial

Rich
Richard@EVUS's picture
What the problem we are

What the problem we are having is that we want the rs485 meter data with the other sensing equipment data to go through the labjack. We currently have temp sensors and CT's hooked up to the labjack and picked up to our scada software (DaqFactory). We want to have the meters as well as the sensors to go through the same system and read by the scada software. The article stated that the usb way would benefit, but we need the whole system as one. How can this be done? 

LabJack Support
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That page briefly says that

That page briefly says that if you don't have to go through the T7 then a USB-RS232 dongle is the best route, but the rest of the page is about have the T7 talk to an asynchronous serial device.

1.  You need to use a chip to get the proper electrical connection.  Maxim has tons:

https://www.maximintegrated.com/en/products/interface/transceivers/rs-48...

2.  You need to know the protocol of your device.  What bytes to send, and how to interpret the bytes it responds with.  Once you know that you write and read the bytes using the asynch registers.

DellyRosen
DellyRosen's picture
Hi....you can utilize the

Hi....you can utilize the Asynch order (Section 4.13 of User's Guide) to compose/read offbeat information, however genuinely you should change the RS485 over to CMOS/TTL. Look at the MAX48xE or MAX308xE from saying ic.com