DH+ overview

My understanding / short explanation is that DH+ is a communications protocol between different devices, that uses channels, nodes and link IDs.

Can anyone point me to some reference material or give a more in depth explanation of DH+? From the beginner level. What types of cabling is required/used? What kinds of devices? What kind of speed ratings? Maximum devices, configurations.

School me.

Throw any info you have at me - I'd appreciate it.

Thank you!

You're on the right track.

Data Highway Plus was the most successful of the Allen-Bradley proprietary networks in the late 1980's. It is used to connect controllers, HMIs, and programming terminals and uses a token-passing peer-to-peer protocol.

Node addresses are expressed in octal; the sixty-four possible node addresses are 00 through 77.

It's a transformer-coupled two-wire system; don't let anyone tell you it's RS-422 !

The data rate is 57,600 bits per second for older devices. Newer ones (and by 'newer' I mean 1988 or so) can run at 230,400 bits/second.

Cables can be quite long; 10,000 feet total at 57.6 kb/s, and 2,500 at 230.4 kb/s.

The Belden 9463 cable has a characteristic blue jacket that led to the common nickname "blue hose" for DH+ networks.

The Allen-Bradley Universal Remote I/O network (RIO) uses identical hardware and cables but fulfills a different function; it's purely a master-slave I/O network. It cannot co-exist on the same wire as DH+ protocol.

Go to the RA Literature Website and just use "Data Highway Plus" as the search keyword.

You'll find classics like the DH+ Product Data brochure, and the Data Highway family networks cable Installation Instructions.

Ken - that is an awesome overview, and great references. Exactly what I was looking for. Thank you!