DeviceLogix

I was doing so reseach on AB and found DeviceNet hardware that has a small simple I/O control. I was just interested in how or when to use this? It looks like it could be a great tool for loose of network control or to free up a network from traffic.
So the real question is when, where, or why should I use it?

DeviceLogix is one of my favorite little technologies. I'll give you a couple of examples.

The 100-DNY42 is a little 4 in/ 2 relay out module that connects to DeviceNet and is usually connected to motor starters and contactors. It has DeviceLogix onboard.

I had a customer who was running large ventilation fans in a fume/gas venting application. If the network failed, it probably meant that control had been lost and the fans needed to turn on to vent gases from the building. But... the louvers and shutters to prevent back-circulation of the vented atmosphere had to be closed and confirmed as closed first.

DeviceLogix let us program that feature into the 100-DNY42. In the event of network loss, the 100-DNY42 turns out Output B to close the louver, then waits two seconds after Input 3 comes on to verify the louver is closed. Then it turns out Output A to actually switch on the fan. We provided independent 24VDC to the DeviceNet at each fan control location so that failure of the network power would not mean loss of ability to control the fans.

Another application was to build a simple "medium-speed" counter out of a normal CompactBlock 4 in/4 out I/O block.

I had an application where the rough positioning of a backstop in a material stacker is done by a pneumatic motor driving a gearbox and a jackscrew. The positioning is done with a "poor man's encoder"; a small DC proximity switch counting sprocket teeth.

The old machine had used local DC I/O modules in a SLC chassis to count the sprocket teeth; this limited the speed of the backstop and required home runs of wire to the main control cabinet.

The new machine had networked I/O to reduce wiring, but that meant that the Inputs wouldn't be reported back to the controller over the network fast enough to catch all these sprocket tooth pulses.

DeviceLogix allowed me to build a simple counter using only the input tied to the sprocket prox. The controller sends a network bit to the CompactBlock telling it to "go to position" after using a MSG instruction to set up the preset of this counter. The CompactBlock checks the Manual/Auto selector (also wired in and part of the normal function of the block) then turns on the pneumatic valve to run the airmotor until the preset count is reached. It then turns on a network "move complete" bit to let the main controller know it's done. I tested the CompactBlock and it can accurately count a 50% duty cycle square wave at up to 1 kHz. We were counting sprocket teeth at maybe 80/sec so I was fine for speed.

DeviceLogix isn't for everybody; I requires some decent knowledge of DeviceNet and the management/programming tools, and obviously won't give good performance on a network whose physical installation is marginal. But it does have the features to turn lowly I/O blocks into fairly smart devices.

I am looking forward to the DeviceLogix implementation over EtherNet/IP in the new PowerFlex 750 series AC drives.

I stumbled on their capabilities by accident when I was configuring some in a network. I've used it in the same manner as Ken; if disconnected from the scanner they can cover their "little island" of control and keep the important things running. Pretty neat little tool to have handy.

Ken,
How do you sent the counter preset over the network? Do you have any programs left that you can share with the public? I see alot of cool projects coming up. If the customer lets me play things will be great. How can the Compact I/O be expanded with out editing the EDS?

Doing things like altering counter and timer presets over the network are not very well documented, purportedly to keep things like that stable and protected inside the DeviceLogix program.

Basically you need to know the type of instruction (the object Class) and the instruction number (each one is numbered, and that's the Instance) and the attribute you want to alter (preset, accumulated, control word).

I think that since the time that I did these, that information has been made part of technotes. I'll go dig a bit.

Ken,
I will look in the KB in the morning. You don't have to spend your time doing research for me. I was hoping that you stoll had the old programs that I could reverse engineer. Let me do a couple of days worth of research to see if I can figure it out before I have to ask . You gave me just the spark that I need to get started.

Jeff.
DeviceLogix is one of AB's best kept secrets. I suspect that this is because widespread use could affect sales of low end PLC's dramatically. I have used Compact Block IO as small stand alone controllers since they first came out and they have been very reliable. The original programming tools used function blocks only but Ladder has been available for a while now which might increase the systems popularity if people actually find out about this functionality.
Andybr