User manual

Computer Gateway User Manual D-1 5/96
D
ASSIGNMENT OF PROCESS UNITS TO CG
Appendix D
This appendix contains information relating to the assignment of process units to the CG.
1. The number of process units that can be assigned to a CG is 63 minus the number of
CGs assigned to the same checkpoint volume. For example, if you have two CGs
assigned to one HM for checkpointing, there can be no more than 61 units assigned.
2. Because the CG node status display shows only points that are assigned to its area and
to the CG node, you can never see more than 36 (area limit).
3. ACP access to parameters in other LCN nodes, both read and write, is independent of
which units are assigned to the CG. That is, it does not matter to which unit the ACP's
ACIDP is assigned.
4. Event Initiated Processing from the HG and CL Messages from the AM and MC are
independent of process unit assignment in the CG.
5. The operator demand of an ACP from its ACIDP detail display requires that the ACIDP
is in a unit assigned to that Universal Station's area, or that the US is in Engineer
keylock level. The same limitation applies to any CG point-parameter that you may
wish to store to, from a custom display.
6. An ACP can send an operator message to only the Unit its ACIDP is assigned to.
Thus, only areas with that unit assigned will receive the message.
7. A process unit can be assigned to only one CG. If there are multiple CGs on the LCN,
each must have a unique assignment of process units.
To summarize, for most flexibility, all units assigned to CGs should be assigned to all
areas that need to communicate with that CG. The units that contain the points that are
accessed by the CG do not have to be assigned to the CG.
In most cases, there is no real need to assign more than one unit to a CG.