ProSoft Technology 5201-MNET-ASCII - Manual (Page 33)

MNET ♦ ProLinx Gateway Modbus TCP/IP Protocol Configuration
Modbus TCP/IP Interface Module Driver Manual
ProSoft Technology, Inc. Page 33 of 78
September 1, 2010
2.6.5 Delay Preset
This parameter sets an interval for each Data Map copy operation. The value you
put for the Delay Preset is not a fixed amount of time. It is the number of firmware
scans that must transpire between copy operations.
The firmware scan cycle can take a variable amount of time, depending on the
level of activity of the protocol drivers running on the ProLinx gateway and the
level of activity on the gateway's communication ports. Each firmware scan can
take from 1 to several milliseconds to complete. Therefore, Data Map copy
operations cannot be expected to happen at regular intervals.
If multiple copy operations (several rows in the Data map section) happen too
frequently or all happen in the same update interval, they could delay the process
scan of the gateway protocols, which could result in slow data updates or missed
data on communication ports. To avoid these potential problems, you should set
the Delay Preset to different values for each row in the Data Map section and set
them to higher, rather than lower, numbers.
For example, Delay Preset values below 1000 could begin to cause a noticeable
delay in data updates through the communication ports. And you should not set
all Delay Presets to the same value. Instead, use different values for each row in
the Data Map such as 1000, 1001, and 1002 or any other different Delay Preset
values you like. This will prevent the copies from happening concurrently and
prevent possible process scan delays.