Ethernet to WIFI hardware recommendations

Need to control a motor on a roof. But can’t hardwire it. So was thinking if I could make the ethernet only plc work on wifi. I saw multiple bridges and what not online. Setup seems a little weird.

Anyone have success with something similar?

The key to reliable control over wifi is to disallow persistent TCP/IP. Only allow bare frames or UDP on a continuous basis. So, Profinet or Ethernet/IP remote I/O technologies. Segregate such control wifi to separate frequencies from general uses. Put an ethernet drive or a remote I/O chassis on the roof with the motor. Configure it to shut down on loss of comms. Have the master PLC on your wired infrastructure for access from Ignition.

1 Like

@pturmel I think you missed my point. I can put an ethernet drive or remote i/o on the roof. But I don’t have ethernet cables on the roof. And I’d like to avoid running conduit through the roof.

For this reason I was looking at wireless bridges. plug device via ethernet into bridge, device is on network. then i can talk to other plc and ignition.

Follow @pturmel advice to the letter! He knows best and safest way to get the job done.

Yes, I got that. Use a wireless bridge device to get ethernet up there. And have a dedicated wifi access point under the roof–one that won’t carry any other traffic.

My key point was to NOT put the PLC itself on the roof. Put the PLC where you do have wired ethernet. Do not let Ignition’s drivers talk over the wifi.

@pturmel Well I was gonna use a micro820 PLC because it is less expensive than a remote i/o. But I’m pretty sure the 525 i got has a ethernet port. So I should just be able to plug it into a gateway and wam bam done. The technical stuff you spoke about is beyond my control but I will let my IT department know what you said.

That being said my OP was still to get recommendations on wireless gateways, not so much the details of the setup.

any hardware you’d suggest?

@pturmel my IT department send me a link to this
I was leaning more towards

Definitely go with the industrial grade device, in a junction box, with external weatherproof antenna. My customers have had great results with the ProSoft RLX2 family, but that might be overkill.

Do not let Ignition’s drivers talk over the wifi.

It is very common to have an HMI, like Ignition, communicate with PLCs over radios. Most SCADA applications work that way. What is your reasoning here?

Wifi is prone to drop packets. This stalls TCP/IP, sometimes for multiple seconds, for packet re-transmission. All the major PLC protocols for HMI/SCADA purposes are query/response on TCP/IP. I/O protocols use deterministic, repeating packets–either UDP or bare ethernet frames–that don’t re-transmit. They just carry on with the next packet.

While a wifi setup can often operate apparently properly with TCP/IP under normal conditions, it only takes a little bit of interference, or a little bit of bursty traffic, to push Q/R protocols into pathological behavior. I/O protocols just keep going.

(Based on my experience with outdoor wifi controls in vehicle-based systems and indoor systems on long rails.)

In one marginal environment I experienced, just having RSLogix 5000 open across the WiFi monitoring one device bogged down the rest of the spread. (Programming software across all brands use very bursty Q/R protocols.)

z-wave or zigbee netwroks connected to PLCs will be better for such applications if any of them support it!

I don’t think it needs to be that intense. I took my laptop to the roof at the cabinet I want to put it in. I got decent speed test results. I’m sure that device with antenna inside will be fine.

If this was a critical system I’d delve in more. But I’m just trying to control the speed and start/stop of one fan. And it’s just an exhaust fan. I don’t want to overkill the process.

I just wanna put the device in, assign the IP, plug it into the gateway, access it remotely.

I’m a little confused by what my IT told me regarding setup. But that’s on them. I just gotta do my part.

Which is why I posted here.

My IT installed PIs on the HMIs and has caused me nothing but headache. Instead of getting a actual PC or thin client they want me to put power switches on the cabinet so production can cycle power to them when they have issues without opening the cabinet.

They are also trying to force me to use barcode scanners for logging into ignition and they suck. I want rfid readers. Barcode scanners in dirty environments with worn badges doesn’t really work well for long. Lol

The problem with an I/O protocol like EIP is that it will continuously write the outputs. That means if you have a setpoint in the output block, that setpoint cannot be changed by a local OIT or the programming software unless you build some kind of INC/DEC pushbutton logic.

We have lots of EIP and that’s not true. You can just change the value in the plc and the device will automatically read it and change.

I/O protocols read inputs and write outputs. Which is what I recommended: an I/O rack or an I/O connection to a drive. Your point doesn’t apply.

@pturmel so plugging a ethernet cable from a powflex 525 to the comm gateway and then connecting the gateway to the wifi would not work?

Does adding a micro820 to control outputs count as I/O? Or do I need a non PLC I/O specific rack.

I appreciate the info, I am researching what you said. Its a lot to take in.

What is going to control your PowerFlex 525 ?

@pturmel i was hoping to use EthernetIP for controlling it with a controllogix plc which connects to ignition.

I.e. program it in the controllogix on the same network. And use ignition to signal the controllogix

That would be perfect, assuming the Logix PLC is on the wired side with Ignition. The 525 will be in the Logix PLC’s I/O tree, I presume. (It typically operates as ethernet/ip remote I/O.) Which means it will use precisely the UDP packets over your roof wifi as I recommend.