Worth Data RF Terminal 7000 - Manual (Page 53)

PromptCOM/ActiveX
Drop-in components are tools that are added to your programming environment "tool kit". There are a
variety of different technologies around for implementing a drop-in component such as VBX (for Visual
Basic) and VCL (for Delphi and C Builder) and COM (ActiveX). Only the ActiveX variety are widely
compatible with almost all development environments.
PromptCOM/ActiveX is a drop in COM component that allows programmers to easily add the ability to
send prompts to and receive data from their RF Terminal via an RF Base Station. It is compatible with
Visual Basic, Visual C++, Delphi, and most other 32-bit development platforms. See the help file for
installation instructions.
Programming Considerations for ActiveX
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 – ActiveX Object
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:
A terminal going out of range and having its power cycled before returning within range OR
Two (or more) terminals using the same ID (terminal ID conflict).
Concepts - ActiveX Object Programming
When you use drop-in components in your program you will follow the standard object-oriented
programming paradigm that uses properties, methods, and events to implement the functionality of the drop-
in component.
• Properties are the various configuration variables used by the drop-in component. An example of a property
is the
ComDeviceName
setting.