RS485 communication

[StefanA]

If you use RS485 to interface a Nano-10 and a HMI touchscreen. Do you need termination and biasing resistors even if they are mounted close together in the same cabinet?  

[support]

It depends on the design of the HMI panel. The PLC does not require biasing resistors for close distance setup, but the HMI may or may not work properly. The MMI6050, MMI6070H and FP4030MR are tested to work with the PLC without the biasing resistors.

[secs]

Hi.

I was looking for a diagram for connecting a f2424 to a mmi6070h. Could you point me in the right direction?

[support]

You can download a general PLC connection diagram for the MMI6050 here:

http://www.triplc.com/documents/MMI6050-cable.pdf

This is applicable to the F2424 for both RS232 and RS485 connection.

[support]

Please disregard the previous document link for the MMI6050, since you mentioned the MMI6070. Here is the cable connection diagram you need:

http://www.triplc.com/documents/MMI6070-cable.pdf

Again, both the RS232 and RS485 wiring is applicable to the F2424.

[secs]

Thanks.

So can I ask, does the rs232 type connection work just as good in a situation where the plc is within 6" of the hmi panel? It seems a lot easier to just use a cable I have laying around.

Also, what setup is needed on the f2424 to allow the hmi panel to work? What I mean is I can plug the hmi on but the plc needs to know there is data being read and written via that port. I realise you have to set up board rates etc but there must be something else to be set so it knows data is to come in and out..

I have previously used the 2424 with my own written software using modbus to read and write and it works flawlessly. But the hmi part is new to me. I am currently doing the graphics etc with the HMI and have that part working but how do I tell 2424 that it will have a hmi panel hooked up?

[support]

Within six inches? If so, yes the RS232 connection will work great under most circumstances. Six feet will work fine too, but the cable could be more sensitive to mechanical/electrical noise interference, so it is recommended to use a shielded cable and to ensure that the communications cable is not in the same conduit as other power/noise producing cables and is not placed next to noise producing machinery if possible.

No setup is needed on the PLC side (other than baud rate and data format) because it is configured to respond to all Host Link and Modbus communication by default (it auto detects the protocol.

You can use the SETPROTOCOL function to fix the com port to Host Link or Modbus.

SETPROTOCOL 1,1 'set RS232 to Modbus RTU
SETPROTOCOL 1,5 'set RS232 to Host Link

[secs]

Many thanks. It just seemed to easy.