Rockwell-automation 284A ArmorStart with ArmorPoint Backplane - Gettin User Manual download pdf (Page 19)

Publication 284A-QS001C-EN-P - July 2006

Theory of Operation

It is possible to connect an ArmorStart product to the Point I/O based subnet

of the ArmorPoint I/O system. This allows the ArmorStart to be connected

to EtherNetIP and ControlNet, along with the original DeviceNet. The

easiest way to program these ArmorStarts is to use RSNetWorx for

DeviceNet software, bridging through the appropriate network. This

ladder logic has been developed as an alternate method of configuration.

Once the appropriate device configuration is done to a User Defined

Structure in the ladder logic file, a bit will need to be turned on in the logic

to trigger a system wide read of the system. This system wide read, goes out

and reads certain attributes of every parameter of every ArmorStart in the

system and stores the information into a large data array. The first attribute

is a flag word that tells the ladder logic if the parameter is read only. If the

read only bit is set, then the ladder logic will skip the additional attribute

reads and will go to the next parameter. If the parameter is writable, then the

logic will read the size, min. allowed value, max. allowed value, the

parameter name, help string and the raw data of each parameter. These

attributes are stored in the data array for use later when the configuration is

written to each ArmorStart. The logic requires that a system wide read

function be completed prior to a system wide write function being

requested.

Note: A system wide read function should be done anytime that a new

ArmorStart is added to the system or an ArmorStart is updated with

a more recent version. This assures that the data array in the logic

matches the total system.

Once a system wide read is done, the raw data of the individual parameters

in the data array can be modified and a system wide write function activated

from a bit in the ladder logic. Only parameters that changed will be written

to the ArmorStart devices, and after a write is done the parameter is read

back and stored in the data array for comparison. If the write and reread

value do not match, an Error Report is generated.

If an error occurs for any reason, during a system wide read or write, an

error report will be logged, containing the device and parameter it occurred

on. Also the status and extended status of the message block is logged in

case the error originated there.

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Rockwell-automation 284A ArmorStart with ArmorPoint Backplane - Gettin User Manual Page 19