Flex IO Comm

Is there a way to connect two communication cards to a flex IO rack? The rack is currently using Devicenet to a 505 and we would like to replace with Ethernet/IP to a CLX. The code in the CLX is new and needs to be tested with the rack connected. I would like to know if the cards have to be installed back and forth until logic tests correctly or can they both be installed at the same time. Also would it be easier to connect Devicenet to the CLX to test then switch over to Ethernet after the logic is good?


Thanks

No way to connect two comm cards to one rack.

What is the need to switch back and forth? If the logic is new then treat it like a new project. Put in the CLX, hook everything up, commission.

f1retank80 said:

Also would it be easier to connect Devicenet to the CLX to test then switch over to Ethernet after the logic is good?


Thanks

Click to expand...

Dump the DeviceNet! It would be much easier to just swap over to Ethernet I/P than to setup the devicenet with a logix and then convert again. Consider devicenet a mistake that should not be replicated! You will find that Ethernet I/P is very easy to setup and run with.

The decision depends on the care with which you are doing the conversion. For most systems, I would do the CPU and network switchover at the same time.

Because DeviceNet requires some labor-intensive memory mapping (even with the Auto Tag Mapping Tool), the tags for the FLEX I/O modules on EtherNet/IP will be different syntax than the tags for the 1756-DNB data image.

My recommendation is to switch to ControlLogix and EtherNet/IP at the same time, and switch back to DeviceNet and SLC-5/05 if the conversion testing fails.

Both the 1794-ADN and 1794-AENT take 24V DC and fit in a similar footprint. Switching between them should take a few seconds.

Take care to practice retracting the FLEX I/O bus connector and snugging it into its place on the first I/O base with your thumb before snapping the FLEX network module onto the DIN rail. If it slips/hangs/protrudes out, there's a risk that you will bend some of the FLEX pins. These modules should never need a large amount of force to seat the connectors, so if you feel resistance, take the assembly apart and examine it before trying again.

Thanks for the reply's!


The short answer I see is no.



I will throw this out to see if anyone has a better answer. I have 6 Flex I/O racks that currently talk to a TI 505 PLC through Devicenet. I am removing the 505 and replacing with a CLX. Downtime is not an option at this plant for more than an hour or so. The plan is to switch the I/O over to the CLX using Ethernet. Then have a message send the points to the 505 until the code is fully tested in the CLX and the 505 can be removed. Any thoughts on a better way to do this without shutting down the plant?

Now you've got my attention

Oh, you meant a Siemens/TI 505-series controller, like a 545, not an Allen-Bradley SLC-5/05 controller ! Thank you for that clarification.

So your DeviceNet Scanner is probably a CTI model 2576.

What's the mix of I/O modules in the FLEX assemblies, discrete vs. analog ? Any unusual modules like the 1203-SM1 SCANPort, or a Modbus module, or a flow computer or high-speed counters ? Is this a high-speed discrete machine control, or a slower continuous process ?

What type of TI-505 CPU are you using ? Do you have any communication modules that can communicate with the ControlLogix, like the CTI 2572-B ?

If you have a 2572-B, you might be able to read the Input and Output data tables of the CTI DeviceNet scanner over EtherNet/IP and use those to run your ControlLogix. You could write logic to not only process the Inputs, but also compare your ControlLogix outputs to the CTI's outputs. You wouldn't have to touch the actual adapters until migration, or install any DeviceNet hardware on the ControlLogix side.

A slightly more involved process might be to install a DeviceNet Scanner on the ControlLogix side (1756-DNB, or 1788-EN2DN) and run Listen Only connections.