I have a measuring device that does not have a button to press when they wish to take the reading. Also it is not practical to give the operators full use of the keyboard. Would it be possible to use a foot switch, mouse button or something else connected into the mouse port which would denote when the reading is taken?
There are a number of possible solutions however it depends on the instrument that you are using. Does the instrument respond to any kind of prompt that you can send it through the serial port? The Software Wedge does have a timer controlled output that can be set up to transmit a prompt out the serial port at a regular interval.
Another possibility is to use a separate program running on a second serial port that could sense changes in the state of one of the hardware handshaking lines and then send a DDE command to the Software Wedge to have it transmit a prompt to the instrument out the serial port. A program is available called Portstat which can be downloaded free of charge and it can be configured to send a DDE command to another program (i.e. WinWedge) when the state of one of the handshaking lines on the serial port changes so you can sense when a switch opens or closes that is wired to the handshaking lines on the port. You could have Portstat send a command to WinWedge telling it to transmit a string out the serial port to prompt your instrument. The only issue with this approach is that you need to use two serial ports on the PC - one for Portstat and one for WinWedge.
Another possible approach would be to control everything from the application that you will be feeding the data from the wedge into. For example, if they are inputting data into an Excel spreadsheet or a custom Visual Basic program, they could write code in their application to prompt the instrument when they need to.