MBLogic
for an open world in automation
Help - System Capacity
Overview:
There is no limit on the number of communications connections or the size of the soft logic program permitted. However, each client or server connection requires CPU time in which to execute. Excessive of communications or soft logic program load can load down the PC's CPU, leaving no time for other processes to execute.
Maximum System Capacity:
The following tests were conducted on a relatively slow PC. A faster PC would permit more connections or a larger program, or a faster polling rate. These samples should be used only as a general indication, and you should observe the readings with your own application on your own hardware to determine actual system load.
Effect of Client and Server Connections on CPU Load:
All connections were made over Ethernet (not to localhost). The server test involved independent clients reading 128 coils at a time (function 1, quantity 128), at 50 millisecond intervals.
The client test involved making multiple connections to a server and reading 128 coils at a time (function 1, quantity 128), at 50 millisecond intervals.
Other tests (not shown here) indicate that system load is mainly determined by the number of messages per second. The size of the individual messages is much less important. Reading or writing one large block of data is much more efficient than several smaller reads.
Effect of Program Size on CPU Load:
The test involved executing boolean instructions at a target scan delay of 50 milliseconds with an instruction mix of:
- 10% STR (push a value onto the logic stack)
- 50% AND
- 20% OR
- 10% OUT
- 10% SET
Note that the soft logic system now operates on the principle of set delays between scans, not fixed scan rates. Actual scan rate will be the result of the sum of the scan delay target plus the time to actually execute the scan.
Effect of HMI Pages on CPU Load:
The HMI client (web page) imposes approximately 3% average CPU load when running the HMI demo included with the system (when the HMI is idle). The graphics used in the demo are (deliberately) very simple. SVG is capable of elaborate special effects which requires a lot of hardware processing. If you decide to make use of some of these special effects, you may wish to check the effect on CPU load and possibly install a good graphics board.