Outputting numerical values from a sensor to PLC via DH-485

esp400 said:

The local is a 7 slot rack. I agree. I think this and a Compactlogix is the way to go. Possibly with the adapter that will allow the Compactlogix to talk to the SLC rack that was mentioned.

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The part you're looking for is a 1747-AENTR. It replaces the SLC processor and makes it into a remote rack.

So all you'll need is a compactlogix, the AENTR card and ethernet flex heads and you got yourself an upgrade

Thanks! That's what I passed along to the people with the $$$$.

The problem with the 1747-AENTR is that it is active mature, even though it has only been available for a relatively short time.

True, but one of the best options

Sometimes the decision-makers can get fixated on hardware cost, even sometimes just on CPU cost.

If I had a tight budget and a few inches of room in the cabinet, I would propose replacing the 7-slot SLC chassis with a 10-slot Logix chassis and some mature used 1756 series hardware instead of finding a new place to mount a CompactLogix and paying for a 1747-AENTR to support just a handful of old SLC-style I/O modules.

You could use a 1756-DHRIO to scan that old FLEX too, and use the serial port on a 1756-L6x CPU to talk to the existing HMI over DH485 (use a 232/485 converter like the 1761-NET-AIC), so those devices could stay in place. A failure of the HMI or FLEX adapter could then be replaced with modern units that support EtherNet/IP.

My brief review of the EtherNet/IP documentation for the Gocator devices suggests that even if you had middleware with the flexibility to read CIP generic Assembly and objects, the hassle of cramming that data into an SLC-5/03's data table structure would be substantial.

The Gocators also use some 64-bit integers for things like encoder positions, time stamps, and frame counts. While 64-bit math is limited even in new ControlLogix, at least basic 64-bit math instructions are available via Add-On Instructions, while it would be a challenge only a hacker could love to handle those in the 16-bit SLC-500 operating system.

There are a handful of ways to go about this upgrade, but middleware that's not a Compact/ControlLogix looks less and less likely to be effective.

Appreciate the perspective Ken. I'll pass it along.

I've definitely broadened my knowledge of mitigating between platforms. Thanks to everyone who chimed in.