Dh+ Network Setup

[Brad Parker 0]

Hello, this is my first post. I am about to connect all of our SLC 5/04 and Panelview 1000 2711-K10G8 on a DH+ network run with 2800 feet of blue hose. Right now as individual systems the baud rate is set at 230.4k and I was wondering if there would be a problem with nodes dropping at this rate. There are 23 SLC 5/04 plcs and 22 PanelViews. If I used a dual channel dh+ card on the PC and split the plant in half would this help?

[Gerry 13]

DH+ is optimised for 16 nodes or less. Your proposed network of 45 nodes will probably have performance problems. The blue hose specs say: 10,000 ft @ 57.6 Kb 5,000 ft @ 115.2 Kb 2,500 ft @ 230.4 Kb your mileage may vary

[Ken Moore 23]

As Gerry mentioned, performance will be less than ideal. However, if these are stand alone systems, what is the purpose of the network? If it's just for monitoring or data collection, the degraded preformance may be okay, it all depends on what you are trying to do. Splitting the network into two segments would be the best option, if you can locate the pc somewhere in the middle, then you can keep the higher baud rate.

[BobLfoot 302]

If you have any volume of traffic between your SLC 5/04's and panelviews I would advise you consider the following. Get a controllogix gateway as follows: 1756-pa72 power supply 1756-A7. install 1756-dhrio cards I'd recommend 5 of these. The older 1756-dhrio only allow one 230k cannel each, I think the newer ones support 230k on both channels. install a 1756-enbt to allow bridging of all dh+ communications to ethernet. You won't need a dh+ card for your pc in this case. I'd reccommend setting up you slc5/04's and pv's in groups of about 4 or 5. you might find some sluggishness once all 23/22 are one network.

[coolhand 0]

I agree completly with what Bob recommended. WE did the same set-up in our plant about 3 years ago. and also put it on the plants ethernet. From there the plant put wireless routers in and now with a wireless laptop can debug ANYWHERE without being tied to a cable. We have over a hundred processors in the plant and now keep all the programs on the network drive. With this anyone can pull up the most current program from any of 4 laptops and back-up on the drive! We also do our data tracking with control logix @ the Gateway. Luke

[rswolff 9]

except for one important thing....If you currently have individual SLC's connected to only a single PV and are using operator controls on the PV's that are mimicking physical buttons. (i.e. to open a lid or to bump or jog a motor). This works fine in this case, but connecting all the units together will normally cause extensive delays in the pb's responses. For simple ON/OFF controls this may be annoying, but for controlling items that require that they react to the pb's state, this is usually unacceptable. As per the DH+ spec, each unit will be allowed One Write and One Request each time it receives the token. So if you panelview app has pb data spread across multiple files it can take several 'laps' to transfer the panelview data. For a six slc/pv network I once worked on, this caused pb delays of up to 3 seconds. If the data is not crucial (i.e. 1-2 second characteristic) you can use the serial ports in DH485 mode and use messaging statements to pass the data to a single receptacle (in my case I used another SLC not connected to the DH+ network). You can then retreive the data from the receptacle to the pc using either DH+, DH485 or Ethernet.

[coolhand 0]

Good point, RSwolff. Our previous data collection system would go out and "ping" the old network about every 10 minutes. This network had about 40 nodes and we did have problems until we split up each line to it's own network (about 5 or 6 nodes) to the gateways' rack of about 7 cards -2 networks per card. It has been a great asset for troubleshooting and maintaining. Luke