LIBRARY ı6ıul 0) - Cranfield University

Appendix E
This Appendix describes the monitoring and control software developed in this
work. The software was specifically designed to be used in a STEIVME industrial
computer using two ARCOM SAD2X250 STE bus based analogue-to-digital data
acquisition boards and an ARCOM SADA-8 digital-to-analogue converter board. The
memory addresses of the former boards were set at E0000h' (board 1, channels 1 and
2) and E8000h (board 2, channels 3 and 4). If necessary, these addresses can be
changed to suit the availability of memory space of the computer by using the set-up
menu of the program. The digital-to-analogue converter board had its port addresses
fixed at 4e8h (voltage channel) and 4e9h (wire feed speed channel). Figure E. 1 shows
the graphical interface of the monitoring and control software in the replay mode,
showing a recorded dip transfer controlled welding trial.
In this mode, a previously recorded weld run can be viewed and analysed
window by window. The top two windows display the transient welding voltage (top
left) and current (top right). The centre windows display the window average values
for the welding voltage (left), the welding current (centre) and the absolute position of
the moving table (right) for the whole weld run. The bottom left window shows the
stand-off estimates as calculated using the dip resistance estimation model and
Ogunbiyi's estimation model. The bottom right window shows information about the
run, the monitoring indices, the set-up welding parameters, the dip resistance (see
equation 6.8) and its standard deviation (see equation 6.9) and the confidence of bad
ignition (see equation 4.11).
The same display format is used during data acquisition and control, the only
difference being on the available functions, accessible through special keys assigned
by the program. Also, the transient waveforms are not displayed during monitoring
and control.
In order to view the graphical interface, the user must go through a series of
text based menu driven screens through which calibration factors can be set and
general set-up functions are available. Also, the software can display values acquired
in the four channels in the hexadecimal form, thus allowing a calibration of the
acquisition boards to be performed.
It should be noted, however, that the control functions can only work if the
system is correctly set-up. For the table control to be performed, the computer must
be linked to the table controller via the serial port 2 and a specific program must be
loaded into the table controller memory. The voltage control can only be performed if
the power source is linked to the computer via the analogue channels (voltage and
wire feed speed).
The following files are needed in order to run the software:
" WCTRL. EXE: main program file;
" WCONTROL. DAT: file containing default set up values;
" EGAVGA. BGI: file containing the VGA functions used for the graphics
screen
I Himal number
239