ProtoLink has developed two I/O servers to support ABB Automation's Totalflow
Measurement product line, which consists of the following devices: FCU, RTU,
and AIU. The first, a 16-bit application suite named TDS, served as a
network distributed DDE Server and was developed using DDEML; hence, it does
not support higher throughput DDE protocols such as Wonderware FastDDE or
Rockwell Software AdvanceDDE.
The more recent 32-bit version, TDS32, acts as an OPC, DDE, and SuiteLink
server. It is capable of supporting installations containing over 4,000
Totalflow devices. TDS32 provides a Windows Explorer-like interface to
allow operators to configure poll groups and monitor current data values and
communication statistics.
One unique feature provided by TDS32 is the ability to lock devices for
writing. When a DDE client pokes a new value to a device data point, that
device is locked in order to prevent other clients from writing conflicting
values. The lock will only be removed after the original client has
instructed the driver to send the new values to the device or to discard the
accumulated pokes.
TDS32 relies on a custom ProtoLink-developed COM object, named TAIServer, which
serves as a common data repository for a number of Totalflow software
applications.
