Limit maximum packets
RSLinx Classic allows values from 5-100 outstanding packets at one time. Certain numbers, such as a PLC-5 on a DH+ network, work best at <30 packets outstanding if only RSLinx Classic is accessing the processor. To determine the best value, change the pollrate to 1 ms and do an advise on the item. If you receive an
Out of Buffer Space
message in the DDE/OPC Event Log, reduce the number of outstanding packets. Limit maximum packets only works on polled reads, not on unsolicited reads.Limit Maximum Packets can be used to make updates more symmetrical for all optimized packets. The default value is 20, but for some PLCs and access methods, it may be necessary to change the default value for better performance, and to reduce communication errors.
TIP:
For a Logix5000 topic, the packet limit is two times the number of connections. For a DeviceNet topic, the packet limit is one.
IMPORTANT:
Collisions are possible when two products talk to the same PLC; therefore, you can reduce, but not eliminate, errors.
Provide Feedback