6-14
Visual Basic, Visual C++, Delphi, and most other 32-bit development
platforms. See the help file for installation instructions.
Programming Considerations for Serial COM
Before making any method calls, make sure you :
•
Set the COM port properties (device name, baud, parity, bits,) as
desired. Make sure the port is closed (call
CloseDevice
) before
making changes to any of the port settings.
•
Call the
OpenDevice
method. This activates the COM port used
by this instance of the WDterm control.
•
Set the
ActiveTerminal
property to identify the terminal on which
you desire to operate. You can change the
ActiveTerminal
at any
time in order to direct commands to appropriate terminals.
Test For Good Communication - Serial COM
Implement an event handler for
OnTermBaseRegister
that causes a beep or
displays a message when called. If communication between the host PC and
the base station is good, your event handler will fire when your program is
running and you power up an attached base station.
Multiple Base Stations
•
For installations using multiple base stations attached to a single host
PC (these were called "channels" in PromptCOM/DLL) simply add a
WDterm
control to your application for each base station.
Terminal Tracking
•
Since you get one set of event handlers for each base station, you will
need some scheme for keeping track of where each terminal (up to 64
per base station) is in its transaction sequence. One possible solution is
to use a "state"variable for each terminal (perhaps stored in an array).
Test the state variable to determine the next prompt for any given
terminal. See the samples for more ideas.
•
It is very important to keep track of "login status" for each
terminal. Every
SignOut
event should have an associated
SignIn
event and a given terminal should not be allowed to
SignIn
twice
without an intervening
SignOut
. Multiple
SignIns
from one
terminal without appropriate
SignOuts
indicate either:
1. A terminal going out of range and having its power cycled
before returning within range OR
2. Two (or more) terminals using the same ID (terminal ID
conflict).
