I am running a Lookout process with an OPC server to connect to a
ControlLogix PLC. My Lookout process will not always reflect the
current state of hardware, i.e. simple Boolean objects do not update
on the display control panel. I can, in some cases cause the display
to change by changing the state of my hardware manually (actuating a
limit switch for example) thus Lookout sees an event and updates the
display. But this does not work in all cases so I have no way of
knowing if the display is accurate.
Similary, changing the position of Lookout switches and pushbuttons
on the control panel will be reflected in the plc ladder logic but not
write back to Lookout to report the change. This is true for both
local and remote position source
s. I should add that switching from
OPC1 to OPC2 or OPC2 to OPC1 can cause some signals to reflect what
hardware is doing but there is no definite consistency that one can
point to that will identify the problem.
Finally, communication between the OPC Server and the PLC is fully
functional and verifiable. So there seems to be a fundamental flaw in
my design any advice on this issue would be greatly appreciated.
Leo
