Experimental Physics and
Industrial Control System

David Dudley <[email protected]> · Fri, 18 Dec 2009 10:07:58 -0500

In the "unconnected" mode, that is correct.  One of the reasons I am working
toward modifying the driver to work in "connected" mode is to be able to get
around those limitations.

Going through the setup of a "connected" mode channel basically gets you a
'handle-id', which directly interacts with the selected remote data.

According to Rockwell, once the channel is formed, you no longer use one of
the 'unconnected' CIP channels, which eliminates the overhead of retrieving
data using TagNames.  Also, once the CIP channel is formed, the remote
device can be set to report data to the host on the 'RPI' (Report Periodic
Interval, as memory serves), or when the data changes.

David

On 12/18/09 1:05 AM, "John William Sinclair" <[email protected]> wrote:

> Note that ControlLogix communications (multicast with tcp messaging)
> includes a fairly severe penalty for using the
> tag names. There are a limited number of cip resources (255 is common).
> Each module consumes several and each IOC access
> by tag name consumes one. As a result, we always use arrays and end up
> in the same old boat of having to do lots of name
> mapping to array position. In principle the tag names are very nice; in
> practice they are not too useful.
> 
> John Sinclair
> 
> David Dudley wrote:
>> For NSLS-2, all configuration and logic is planned to be incorporated
>> into the IRMIS system, as a single database layout.
>> 
>> In addition, I should have initially mentioned that one of the primary
>> reasons for the A-B choice is that it uses a communications format
>> named ?CIP¹, and its internal memory configuration is entirely driven
>> by TAGNames.
>> 
>> In tne ControlLogix platform, you do not do programming or
>> configuration by having to remember or know things like ³...
>> ?B-703:R-E5<OTB>T-1¹  is wired to terminal IW102... (That¹s Building
>> 703, Room E5, Optical Testing Lab, Temperature 1)² .
>> 
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System