W&T Com-Server++, Manual

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181
W&T
OPC data transfer
Subject to error and alteration
22�4 Serial OPC variables
T h e O P C S t a n d a r d s D a t a A c c e s s 3 . 0 ( D A 3 . 0 ) a n d
Alarm&Events (A&E) are supported by separate OPC Server
instances.
If the client used does not support the browser function for
servers and items available in the system, the following na-
mes must be used:
OPC server DA 3.0:
Wiesemann-Theis.Network-IO
OPC server A&E: Wiesemann-Theis.Network-Events
Serial communication for each installed Com-Server takes
place using the following variables. In contrast to the OPC
Server names, these can be freely set using the configuration
tool:
TxD: (VT_BSTR, W): RS232 send data, assigned values are out-
put over the serial port.
RxD: (VT_BSTR, R): RS232 receive data (the last text packet
which arrived from the serial port).
N: (VT_I4, R/W): Packet counter, is incremented by 1 each
time a text packet is received.