Hardwire vs Cat5

[ptonsparky]

I am an electrician at heart. Hard wired everything as I grew.


Just lately I set up a couple CLICKs via a LAN. First for me. I did not want to pull several hundreds of feet of control wires vs one Cat5. Works well.


Now we are looking at adding High limit switches to bins that will be a nightmare to get conduit up and am thinking of adding a 3rd CLICK at bin top with one Cat5 down. It is tough to see a downside to this method.
What is the downside? (Other than most of the electricians in the area would not have a clue on how to troubleshoot.)

 

[Cow]

Tom, I'm the same way, hard wiring for everything, it's simple, everyone can troubleshoot it.

But, last summer we did a large feed mill with lots of motors and limit switches. Like you, I also made the decision I'd rather run some Cat5 and 3 #14's for power than a bunch of control wiring. I used a Do-More PLC for the project. I had the main rack plus another local rack in the same cabinet, and two more remote racks situated closer to some more equipment. It was so much easier, the guys liked not having to pull all that extra wire too. It was a win-win.

I would do it again in heartbeat.

 

[steve66]

What if you loose communication? Will everything stop, or will the bin overflow? Is it a big deal if the bin overflows, or is it just a mess?

I'd still prefer to hardwire safeties and interlocks, but it may depend on important the interlock is, and how much the client is willing to spend.

 

[just the cowboy]

As long as you use handshaking

As long as you use handshaking

It is just like having a remote rack in the old days. Just make sure you use some type of handshaking to check for loss of communacation.

 

[FionaZuppa]

what is meant by "Cat5", you mean twisted pair cat-5 ? sounds like the wire is not the issue, its the connector ??
you also mention LAN, as in the cat5 is using a LAN comm protocol? or is it just that the cat5 is using the twisted pairs as on/off type of signal?

 

[ptonsparky]

What if you loose communication? Will everything stop, or will the bin overflow? Is it a big deal if the bin overflows, or is it just a mess?

I'd still prefer to hardwire safeties and interlocks, but it may depend on important the interlock is, and how much the client is willing to spend.

Loss of communication would, if I do it right, stop the fill. Not life or injury threatening. Of course someone could throw their back out scooping product.

 

[zbang]

you also mention LAN, as in the cat5 is using a LAN comm protocol?

Yep, if you're using CAT5 to carry an Ethernet-based LAN (like the CLICK Ethernet PLC), you'll need a network switch to connect all three legs (top device, bottom device, feed from remove controller). Google for "industrial ethernet switch" and you'll find a pile of them.

Can you link the top and bottom devices over RS485 instead of Ethernet? That would eliminate the switch.

 

[kwired]

What if you loose communication? Will everything stop, or will the bin overflow? Is it a big deal if the bin overflows, or is it just a mess?

I'd still prefer to hardwire safeties and interlocks, but it may depend on important the interlock is, and how much the client is willing to spend.

Depends on the skill of the one writing the program to know what it does when a failure occurs.

Tom, you could even eliminate the Cat V and go wireless networking, but depending on how critical the loads are a single Cat V is still much less installation then many, many control wires, especially if there is some distance between major distribution points of those control wires and the wired network is usually more reliable then wireless.