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rs485 full duplex


ma Apr 11, 2022 07:23 PM

does anyone know how to connect a cr1000 to a sensor using rs485 full duplex. All I see are half duplex examples.

Marco


JDavis Apr 11, 2022 10:09 PM

When you set ComC5 to full duplex RS485, ComC5 is the transmit pair and ComC7 is the receive pair.


JDavis Apr 11, 2022 10:10 PM

Tx- = C5

Tx+ = C6

Rx- = C7

Rx+ = C8

0V = RG


nsw Apr 12, 2022 07:23 AM

Hi. To avoid confusion on this, if you have a CR1000X datalogger, then JDavis posts above apply.

If you have a CR1000, it does not natively support RS485 sensors or devices in full or half duplex.

You can add an expansion module to support RS485 by adding the SDM-SIO1A or SDM-SIO4A :-

SDM-SIO1A: 1-Channel Serial I/O Module (campbellsci.com)


Thein Apr 13, 2022 03:06 AM

Hi nsw, a bit confused before seeing your message.What is the difference between MD485 and SDM-SIO Module? Can SDM-SIO Module be used inconjection with AM16/32B?


nsw Apr 13, 2022 08:58 AM

Hi Thein. You are correct, the MD485 can be used to connect a CS I/O port to another device which is RS485. The SDM-SIO1A or 4A connects the datalogger using the SDM bus : Control ports C1, C2 and C3 on the CR1000. As its a bus, upto 15 of these can be connected to give 15 offf expansion ports. The SDM-SIO1A is not used with the AM16/32B.

Both could be used to give RS485, but the MD485 is more expensive than the SDM-SIO1A. The MD485 tends to be used mainly for communications between multiple dataloggers and a connection to a PC with LoggerNet. The SDM-SIO1A or 4A is not normally used for datalogger to datalogger or PC comms as it does not support PakBus comms.


JDavis Apr 13, 2022 02:28 PM

MD485 will not do full duplex RS485. So, the recommended interface for 1 sensor would be a SDM-SIO1A.


ma Apr 17, 2022 03:36 AM

Thanks to all for the response. I hope one day the cr1000 will natively support rs485 full duplex since it appears to have enough com ports.

In the meantime I am going to flip to a cr1000x and avoid extra parts.

Thanks

All

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