CAN over T1

[Schmoleskin]

Trying something new, in Yellowstone Park. The park has a few generators here and there, but are finally installing a T1 line between a couple of sites. This should allow them to have the capability to loadshare in isochronous mode during utility outages, between distant units, as their load continues to grow and change with the seasons. They've tried to operate for years with some rather cleverly conceived PLC programming to try to keep load and frequency balanced without communications, but it is doomed to fail, and regularly does, in many scenarios.

We are installing new generator controls, voltage regulators, etc. We're using the Woodward EasyGen load and sync control, and have quite often, but are used to the CAN lines being tens of feet long, not tens of miles. The additional complexity of the T1 line is not a regular challenge for us.

The inter-controller loadshare line is a CAN connection, and then a CAN to Ethernet interface (Proconx CAN-ETH), then on to the T1 modem(s) shown in the attached photo (Westell DTWA-528-01).

The Proconx is here:

http://www.proconx.com/can-ethernet-converter-gateway

The Proconx CAN-ETH converter (from manual) "... encapsulates CAN messages into UDP packets and transports them via Ethernet. The gateway can operate in peer-to-peer or broadcast modes." We have someone here that has that device covered, we use another almost like it for the HMI, the rub is the T1 modem...


I've read through the manual for the modem:

http://sitefinity.westell.com/docs/extranets/dtwa528-01l4-8-16_030.pdf

Unfortunately, I'm not conversant enough with Ethernet/DSL(?) protocol to know the difference between the 3 possible configurations, DDS, DS1, and Voice. They appear in the photo, but not in the instruction manual. I'm going to get on the phone with their tech support line later today, but I'm hoping this may be something one of you folks is familiar with.

Two questions:

1) Which is the proper modem setup of the 3 (DDS, DS1, or Voice)?
2) Do I need to construct a special Ethernet cable between the modem and CAN adapter, or is a standard straight through or crossover required?

Thanks, as always.
DaveO

 

[MikeHalloran]

2) The connectors are identical, but pinned differently.
It looks like you need a special cable.
I'd guess you can buy the exact correct cable from your equipment supplier(s),
which I would recommend if your labor is worth anything.
Failing that, I would buy a custom cable from blackbox.com.
Homebrew cables are my last choice.

http://www.differencebetween.net/technology/difference-between-rj45-and-rj48/

http://www.arcelect.com/rj48c_and_rj48s_8_position_jack_.htm

Mike Halloran
Pembroke Pines, FL, USA

 

[robertjo24]

I guess the first question is, are these point to point T1s?
Are they full T1s or fractional T1s?
Unless I’m missing something, you need a router at each site. The Westel box is usually a network interface card that allows the telco to monitor and test (loopback) the T1 remotely, more commonly referred to as a “Smart Jack”.

The local router serial T1 interface would plug into the T1 CPE (customer provided equipment) interface, and would be programmed to route traffic between the sites. The back end of the router would be programmed for the local area network (LAN), where the CAN Ethernet adaptors would plug in.

Again, I may be missing something but that’s generally how it’s done.

 

[robertjo24]

Of course, if you have a true point to point T1, you can use a simple T1 Ethernet extender. It’s basically a bridging device that negates the need for a true routed network. They are available in single port and multi-port models that allow multiple devices to interconnect between sites.
I probably wouldn’t extend a PC over the link but it would probably work fine for the CAN converters.

This link is an example from BlackBox

http://www.blackbox.com/Store/Results.aspx/Networking/Extenders/Ethernet-over-T1/n-4294953143

 

[larrym]

If you are running data only on the T1 then it needs to be configured as a DS1. The T1 output from the westel box needs to connect to a router at each end that converts the T1 signal into ethernet that the Ethernet to CAN Bus media converters can connect to.

As per usual...some assembly required...

Larry

Larry Mackey