Devicenet Solenoids and I/P's

[Greg Dake]

Greetings everyone,

I'm doing a project which will involve the use of about 16 solenoids and 3 I/P transducers. I will have a Devicenet network for the 11 VFD's I'm controlling and figured I'd try to pickup the solenoids and I/P's as well on the network to minimize hardwire I/O.

I have looked at Devicenet solenoid banks from Festo and SMC, as well as Devicenet I/P's from Fairchild. The problem is they are not very cost effective in relation to hardwired solenoids and I/P's.

It's just hard to justify Devicenet solenoid banks because the cost per I/O point for discrete outputs on a PLC is relatively low.

Does anyone have any experience with Devicenet solenoid banks and I/P's which are a little less expensive?

TIA,

Greg

 

[curlyandshemp]

Greetings everyone,

I'm doing a project which will involve the use of about 16 solenoids and 3 I/P transducers. I will have a Devicenet network for the 11 VFD's I'm controlling and figured I'd try to pickup the solenoids and I/P's as well on the network to minimize hardwire I/O.

I have looked at Devicenet solenoid banks from Festo and SMC, as well as Devicenet I/P's from Fairchild. The problem is they are not very cost effective in relation to hardwired solenoids and I/P's.

It's just hard to justify Devicenet solenoid banks because the cost per I/O point for discrete outputs on a PLC is relatively low.

Does anyone have any experience with Devicenet solenoid banks and I/P's which are a little less expensive?

TIA,

Greg

You have come to the same conclusion we have in the past. We have always found to be more cost effective to use block I/O and hardwire the solenoids.

Only time D-NET I/O is practical is when you want the LCF sticker (Look Cool Factor)

Ian

 

[Andybr]

Greg.

I have been using Festo CVT valve terminals for more than 5 years now and:-
i)I have found them less expensive than individual valves once cabling, stainless steel cable tray etc. has been considered.
ii)I have never had a single failure.
I would happily recommend them to anybody but you know your installation better than I do.

Andybr

 

[mellis]

DeviceNet can be cost effective, it depends on the project.

A few points:

The cost of DeviceNet enabled field devices will probably be higher than that of hardwired field devices plus I/O cards.

The cost of DeviceNet wiring materials will probably be higher than wire and conduit too.

The cost of labor to install and wire a DeviceNet system *can* be lower than a hardwired system.

The cost of additions and modifications to a DeviceNet system *can* be lower than a hardwired system.

Conclusions:

If you focus on the hardware costs, DeviceNet will always look expensive.

If a DeviceNet system is to be cost effective, you need to make up the additional hardware cost in labor savings. Or at least minimize the difference in cost. Realize that people that are inexperienced with DeviceNet will probably over-estimate DeviceNet installation and under-estimate hardwired installation. Comissioning time is often overlooked as a labor cost. Since this is typically where my labor comes in, I am especially sensitive to it. My personal experience is that I spend a lot more hours detecting and repairing traditional hardwired systems than I do for DeviceNet. I have some DeviceNet horror stories too, but overall I like it.

If your system requires frequent additions with minimal downtime, that may be enough to support DeviceNet even with a higher pricetag. It only takes a few hours at $10,000/hr downtime to make DeviceNet look cheap. This is not always an easy argument to make when the system is first built. But, it can make some true believers if the same project team is involved for the expansion project.

Personal Preference:

QuickLink flat trunk with sealed IDC connectors. I highly recommend it for wiring. The ability to physically add new drops to a running system is great. You still have to take down the DeviceNet to add them to the scanner, but the downtime can be very short.

 

[hd_coop]

Does anyone have any experience with Devicenet solenoid banks and I/P's which are a little less expensive?

We have a conveyor here with a lot of 1794-ADN devicenet adapters for Flex I/O which works pretty good for us.

 

[Joe_WaZoo]

The blue covered node in this picture is a SMC valve bank that is a Node on DeviceNet:

Exhibit 1

Here are some other SMC valvebanks that are nodes on DeviceNet.

Exhibit 2

And here is a picture of some standard valves that are controlled by the outputs on the DeviceNet node next to the valve.

Exhibit 3

Joe_WaZoo