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Topic: Interfacing with External 8I/O board (Read 386 times) previous topic - next topic


Hi Everyone,

My son and I are new to this awesome device we  just received our Arduino UNO starter kit and used his phone with Blynk to contol his first command via wifi. :)
I am a electrician whom programs commercial VSDs and PLC units to control large motors and manufacturing plants.
Just wanted to ask the question not sure if iam posting in the correct forum but i have a Emerson multiplex card that has RS485 bus connection which consists of  8 outputs and 12 inputs with 5v and 12v signals and Also analogue and Digital outputs thats sends 0-10v signals or pulse 8vdc is it possible to connect the Arduino via the RS485 network modbus onto the Emerson card read the inputs and control the Outputs?

1.Can this be achieved ?
2.Where can we read further or video information to make the interface  between Arduino ?
FurtherDetails of the card:-
MultiFlex I/O Board Installation and Operation Manual
PDFwww.emersonclimate.com › Documents

3.Also whats a good starters book how to program Arduino Thats kids friendly?

Syphon and Son


if you do a web search for arduino rs485  you will get plenty of links to suitable RS485 interfaces and examples of projects using them


Thanks for providing the start. Not sure how the Arduino will be sending and receiving commands from the card 3rd party card ?

Is there any specific website that provides sketches and detailed information on how to establish the command?



Nov 12, 2017, 09:29 pm Last Edit: Nov 12, 2017, 09:37 pm by horace
have a look at

the RS485 modules are available on EBAY - search for RS485-Modules arduino
it is probably worth getting a USB/RS485 module for a PC to help with debugging - search for USB to RS485 TTL Serial Converter Adapter


Nov 14, 2017, 01:08 am Last Edit: Nov 17, 2017, 12:20 pm by Syphon72
Thanks for the guidance have done some reading and further depth research on Rs485 networks how they communicate and operate.
So let me summarise what my understanding is so far:
The Arduino uno will be the Master unit which will rececive the commands and comunicate them through to the emerson output input card  which will be the slave unit.via a Rs485 modbus connection.
I need to connect the multiplex card to a software onto a Pc via modscan and retrieve the output and input registers.
Once these registers are obtained we need to include them in the sketch?

Is this correct?
Then how do we code the sketch to send and receive the commands?
What libraries do i need to look at?

Not sure if i am on the right track???can i have some assistance ?

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