W&T Electronics 57661, Руководство пользователя

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Subject to errors and modifications
After clicking on the Save button all the settings are updated in
the Web-IO and the start page is reopened in the default user
mode. The Web-IO can now be accessed by the OPC server.
3.9.5 Program options
After clicking on General options you can specify some details
about the behavior of the OPC server.
Release I/O devices: In this context „release“ means
disconnecting the network connections to the devices so that
other applications can again have access to them.
Watchdog (VT_R8, R/W) is a global OPC variable, i.e. not
associated with any any particular I/O device. It contains a
seconds value which is continually counted down if this option is
enabled. As soon as a value of 0 is reached, the I/O devices are
released. Please note: Even if obviously only an OPC-DA client
can prevent the watchdog from being turned off (by writing over
and over a watchdog value other than zero, e.g. sending the value
15 every 10 seconds), both DA and A&E clients are also affected.
If no OPC clients are still connected: Depending on the
device type it may take a while (even several seconds for a Web-
IO Digital!) until a closed connection can be opened again and
the the OPC server resumes providing valid values.
Limit update rate: An attempt to read values from a device at a
faster rate than it can actually provide those values results in
the OPC interface always finding itself in timeout situations.
The affected DA variables then continually swing back and forth
between OPC_QUALITY_GOOD and OPC_QUALITY_BAD, which
makes them effectively useless. To avoid such a situation OPC
clients are prevented by this parameter from setting too fast an
update rate.