User manual
Computer Gateway User Manual C-1 5/96
C
TIMING DATA AND PERFORMANCE CONSIDERATIONS
Appendix C
This appendix contains information on performance and CG database size.
C.1 CG PROCESSING RESTRICTIONS
The host processor should limit each ACP to one request message at a time.
The CG allows the host processor to send multiple messages and can stack a maximum of
20 messages for processing. Actual concurrent processing, however, is limited by space
limitations and by limitations on specific message types. Examples of these limitations are
Continuous History 4, Single Point Get/Store 1, Multi-point Get/Store 4, Miscellaneous
Functions 1, and Build Internal DDT 1.
If the CG message-receiving capacity is exceeded, it sends the expected response message
with a return status indicating that its queues are full.
C.2 CG PERFORMANCE LIMITS
When transferring data by Internal DDT, it is important to realize that there is an overhead
associated with processing each request. It is, therefore, inefficient to use Internal DDTs
with small numbers of points. Where throughput is important, Honeywell recommends
that nonhistory Internal DDTs should contain at least 200 point-parameter definitions. If
the points come from multiple LCN nodes, the best use is made of TDC 3000
X
's parallel
processing capabilities and best performance is realized.
Following are some of the limits on the CG's ability to share information with other nodes
on the LCN:
Response to other nodes for ACIDP or CRDP values—45 parameters per second.
Get or Store of values to other nodes (table driven at 300 parameters per Internal DDT)—
1.5 DDTs per second (of type Real).
Get or Store of Whole Array—1000 parameters from another node in 2 seconds.
Get History—80 'points' per minute (assuming 60 values per point for one minute
snapshots).
CG performance may be affected by other loads placed on its information sources and
destinations (HG, AM, HM), as well as loads placed on itself for display of ACIDP/CRDP
information, activation of ACPs, etc; therefore, these figures must be considered
approximate. It is recommended that users update a cluster-loading analysis when a CG is
added to their system.