Shielding Profinet ?

Hi,

I got a question about electrical shielding.
For profibus in the past, shielding was a must and important.

I still remember that we did the following standard shieldment methods:
- Analogue signal cables: 1 side shielding (antenna)
- Frequency converter motor cable: 2 side shielding
- Profibus: shield on every cable that enters the closet.

What about profinet...
Some integrators still do shielding on the backplate in closet like profibus cables, but some don't. Is it a must... what are the basic rules about profinet cabling ?

Thanks,
Kind regards,
Combo

You must use Profinet cables. These always have the shield.

For cables that exit the cabinet, you should definitely have shield terminals, like these:
https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcT-mriYYAXQ3HZEP2aXojU6oxJcW3OoOGR3xOUlW1EPVKHyjyxz0DlXCW4
IMO it is a must-have.

For panel-internal cables, it may be enough with the ground connection in the connector.

I personally prefer to shield any cable that carries data or signal. The additional cost of shielded cables is usually less than even one time of hunting down an intermittent fault that is being caused by noise. It can be difficult to isolate and even worse to rip-out non shielded cables and replace with shielded after the fact.

Especially when the noise causes degraded system performance and not a true fault, the money that can be lost in product quality and/or cycle time can be a hidden cost that typically grows with time.

tnx

Thanks Jesper

JesperMP said:

You must use Profinet cables. These always have the shield.

For cables that exit the cabinet, you should definitely have shield terminals, like these:
https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcT-mriYYAXQ3HZEP2aXojU6oxJcW3OoOGR3xOUlW1EPVKHyjyxz0DlXCW4
IMO it is a must-have.

For panel-internal cables, it may be enough with the ground connection in the connector.

Click to expand...

Can you get by without it? Usually, except when you can't.

dlweber is right, just get them. They pay for themselves once you consider troubleshooting.

Originally posted by mk42:

Can you get by without it? Usually, except when you can't.

Click to expand...

Very well said. I think it's important to acknowledge that it can, and often will, work without shielded cables while also stating that it is a problem waiting to happen, and a very difficult one to diagnose at that. There are just too many working unshielded applications out there today to emphatically state it will never work.

Keith

kamenges said:

Very well said. I think it's important to acknowledge that it can, and often will, work without shielded cables while also stating that it is a problem waiting to happen, and a very difficult one to diagnose at that. There are just too many working unshielded applications out there today to emphatically state it will never work.

Keith

Click to expand...

Interestingly, the newer Ethernet standards for cables are doing away with unshielded cables as an option, but these are only needed for crazy fast speeds Apparently 40gig is coming over copper in the future (Cat 8 cables)

We custom fit our cable lengths to the devices on the equipment. Yes...industrial grade Ethernet cable, 2 pair shielded...... but I have been changing to 4 pair for full support of Profinet Gigabit communications.

Inside the cabinet, for short runs to switch, I just use shielded CAT5e (or better) industrial rated patch cables from Automation Direct or...
https://www.automationdirect.com/ad...t.)/cat5e_patch_cables_(shielded_twisted_pair)

Once again..... maintaining 4 pair wiring to support Profinet gigabit devices.
yes...it is shielded....but not necessarily independent pairs shielded., however we are talking less than a 3 ft run in cabinet to switch.

As Profinet works over the regular Ethernet media, whatever works for Ethernet, should work for Profinet as well.

However, using shielded network cables is a better option for industrial environments where, unlike office, sources of strong electrical noise can exist.