Need communication between G400 and G120

[EvoMotors]

@michaelb

@EvoMotors

@ Evomotors
I assume the I don’t need a DB9 cable and both RS232 and RS485 will work using 10 meters 4 cores 20GA shielded cable. Is my assumption correct?
So the RS232 is full-duplex and single channel RS485 is half-duplex and I can still communicate both ways but not simultaneously?

The RS485 module from GHI is half duplex, and you are correct you can still communicate both ways, but not simultaneously. Their are Uart - 485 drivers that are full duplex, but you would need to make your own.

That said, there are lots of off the shelf RS232 - 485 converters at full duplex available, so If you designed with RS232 as Dave suggests, and found that their was problems, you could simply drop in an off the shelf converter at each end and have a RS485 link with no changes to your code.

The same drop in replacement from RS232 holds true for industrial wireless modems from Laird / Microhard ect, In my designs I’ve used RS485 up to approximately 300m, but have found that moving to wireless solutions, often provides a more robust connection than wired designs.

Still if you already have wireless Ethernet on one module, I would go with adding wireless on the G120, and simply communicate over the network.

Adding wireless to G120 is not an option for me as WiFi connection on the G400 is optional, it will only be used for monitoring and remote control. I’ll incorporate IC ST3222E to my design in both PCBs and see how it works.

Thanks.

[Gene]

Don’t forget RS422. It is a full duplex version of RS485 but needs a minimum of 2 twisted pairs (one pair for RX and one pair for TX) plus a ground wire. If instead of the Gadgeteer RS232 module you use a digital (aka TTL) to 422 converter (check B&B electronics, Moxa, Blackbox or Sparkfun and make sure the input voltage of the converter matches the output voltage of your UART: probably 3.3 volts), you can signal faster over longer distances and full duplex. You can use all the standard .NET Micro or Gadgeteer serial resources and your software doesn’t need to know that you’re using RS422. RS485 uses the same signalling technique with the same throughput and distance but is designed to share 1 pair of wires for RX and TX hence the single duplex limitation.

Here’s a nice reference: Your Go-To Source for Innovative Solutions

[Mr_John_Smith]

@ EvoMotors - You sure change your logo often.