Maximum Length of DH+ Cable

Hi.
I have a plan shown in picture below.
I want to know can I use DH+ network without any repeater/optical fiber/...?
I've read AB cabling manual, but I didn't understand meaning of "Trunkline" and "Dropline". Can someone tell me about these please?
Thank you

First question: Why on earth would you want to use DH+? It's a proprietary protocol (meaning the hardware will be very expensive), it's slow, and Rockwell has been sweeping it under the rug in favor of Ethernet/IP for over a decade. Is this because you're using existing equipment? If that's the case then I understand. Despite the fact that it's becoming less and less supported, there is still a HUGE install base of it out there.

Secondly: As far as I know, DH+ is something that is usually daisy-chained, and you put a 150 ohm termination resistor on either end of the network. It doesn't HAVE to be of course, but that makes it a lot more complicated. I've never seen "trunk line" and "drop line" associated with a DH+ install. Usually it's just blue hose and that's all there is to it. Oh, and the distances you're showing here don't seem unrealistic. The thing about DH+ is that the longer the cable, the lower the speed. 56K is about the slowest you'll get though. But where I used to work we had DH+ going these distances and never had a network problem. No repeaters or special equipment, just termination resistors.

Those terms do apply to Devicenet, though. Trunk line is thicker and not meant to connect to any devices, but just provide the "backbone" of the network. Drop lines connect the devices to the trunk line. These are usually thinner. Lots of people make the mistake of connecting trunk line to devices. This can cause problems like the weight of the cable pulling on the connector and causing communication interruptions. Think of it like a limited-access highway system. The trunk line is the divided highway, and the drop lines are the entrance/exit ramps.

But again, I've never seen those concepts associated with DH+

They did make a station connector:

43472 - 1770-SC : Station Connector Information

Data Highway Plus maximum cable length of the trunkline is 10,000 feet (3050 metres).
Dropline cables must be no more than 100 feet (30.5 metres) in length.
If possible, keep the dropline cables longer than 10 feet (3.0 metres) in length.

This is for 56.7 KB. I *think* for 230 KB, the length is a quarter of that.

Thanks for your answers. Yes, it is because of old equipments. (this is a revamping project)... Sorry I'm confused! Can you please tell me a simple yes or no answer? Can I use DH+ here? Thank you again

Do you have the DH+ modules for the PV+ ver. 6? I thought they were not available for the newer PV+.

The PanelView Plus 6 discontinued support for the RIO Adapter driver on the 2711P-RN6 module. The DH+ driver for that module is still supported.

So the simple answer is 'Yes'.

brstilson said:

First question: Why on earth would you want to use DH+? It's a proprietary protocol (meaning the hardware will be very expensive), it's slow, and Rockwell has been sweeping it under the rug in favor of Ethernet/IP for over a decade. Is this because you're using existing equipment? If that's the case then I understand. Despite the fact that it's becoming less and less supported, there is still a HUGE install base of it out there.

Click to expand...

Little aggressive aren't we? Pretty clear from his diagram he's talking to PLC5's, which aren't exactly known for the on-board Ethernet capabilities. Clearly it was an existing system, and while yes it's out-dated it's damn-near impossible not to make it work, just like RIO. I've seen enough splices, wire nuts and electrical tape holding DH+/RIO networks together over the years, you won't get away with that with many other protocols... Certainly not saying it's acceptable but if you gotta keep a plant running, well duct tape could certainly fix a DH+ network in a pinch.

I was told a story that at Automation Fair 1997 in Nashville, there was a DH+ demo running on an actual barbed-wire fence.

Ken Roach said:

The PanelView Plus 6 discontinued support for the RIO Adapter driver on the 2711P-RN6 module. The DH+ driver for that module is still supported.

So the simple answer is 'Yes'.

Click to expand...

Thanks for the clarification. I knew one adapter was discontinued. Does the physical comm module support both DH+ and RIO and just the driver is discontinued.

Thanks all of you.
So, I'm gonna apply this project.
Thank you for your support.

padfoot said:

Thanks all of you.
So, I'm gonna apply this project.
Thank you for your support.

Click to expand...

With that many PV's on the network don't expect it to be fast. When there is that much traffic on the "Highway" you will get some "stop and go".

Thank you Mickey. I've another plan with Ethernet network. Maybe I'll think about that!

Paully's5.0 said:

Little aggressive aren't we? Pretty clear from his diagram he's talking to PLC5's, which aren't exactly known for the on-board Ethernet capabilities. Clearly it was an existing system, and while yes it's out-dated it's damn-near impossible not to make it work, just like RIO. I've seen enough splices, wire nuts and electrical tape holding DH+/RIO networks together over the years, you won't get away with that with many other protocols... Certainly not saying it's acceptable but if you gotta keep a plant running, well duct tape could certainly fix a DH+ network in a pinch.

Click to expand...

I didn't mean to sound aggressive. I guess I should have assumed it was existing. I have seen brand spanking new PLC-5s in the last couple years, though. Sometimes specs don't get updated.