CTI 2572-B / 2500C-2572-B Installation and Operation Manual 64
Performance is substandard. You are making heavy use of the Client
function in combination with the Server
Don’t trigger the Client command
more often than required. Split
the load among multiple modules.
Module is located in a remote base. A
Special Function module such as the
2572-B is considerably slower in a
remote base and may increase scan
Place the 2572-B module in a local
base.
A network station is transmitting an
excessive number of broadcast
packets. Broadcast packets consume
processor resources of every station on
the network.
Use the module diagnostic facility
to capture the count of broadcast
traffic. Use a network analysis tool
to analyze the broadcast traffic on
the network. If a problem is
found, remove the offending
station from the local network or
segment the network such that
broadcasts are not propagated to
10.6. PLC Logic Problems
As described previously, the Command Block located in V memory specifies the command to be executed.
The Command Slots (WY5-WY8) select which Command Blocks are to be processed. The Command Control
bits trigger the execution of the commands. A mistake in setting up and/or manipulating these structures will
cause erroneous results. Fortunately, the 2572-B module provides extensive error reporting which should
assist you in correcting logic problems. See Appendix A for a complete description and typical solutions to
resolving the errors.
Following are some common errors in using the PLC interface to the 2572.
Command Block Errors
When you are first setting up the command blocks in V memory, it is easy to enter incorrect data into the
command block or to omit data from the command block. Some mistakes, such as an invalid command or
port number will be obvious, because the 2572-B will return an error when they occur.
Command Slot Errors
Other errors can occur if you enter the wrong V memory address for the Command Block or when you omit
entering an address. If you enter a V memory address which does not contain a valid command block or enter
an address of 0, the 2572-B will raise the PLC ERR bit as well as the CMD ERR bit. No error code will be written,
since there is no valid location in which to write one.
NOTE:
A command block is considered invalid if offset 2 (Connection Number) does not contain hex 4B is
the high byte of the word. This signature byte places all connection numbers are in the range of
19201-19299 decimal (4B01-4B63)
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