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which would become active by setting a dedicated robot output directly connected to
it. The digital output of the touch-sensor was connected to a digital input in the table
controller to indicate when it should stop during a welding joint search routine. In the
implemented system only five robot outputs and three robot inputs were found to be
necessary. However, a larger number of digital channels could be used in a more
complex system. The five robot outputs could indicate up to 32 different situations,
which could be assigned in a look-up table.
Table 6.10 - Digital connections between the control subsystems
Robot I Interface Box I BDH 550 I Touch Sensor
Output I-t- 24V Output Input 0ý
Output 2 24V Output Input 1
Output 3--r-24V Output -ý-Input 2
Output 4 24V Output Input 3
Output 5---ý-24V Output ---' Input 4
ii
Output 6 24V Output
Output 7-j-See Figure 6.8 III
Output 8--t-Switch Output
Input I 24V Input Output 8
Input 2-ý--24V Input -ý-Output 9II
Input 3 --ý-24V
Input 4 --ý-Not
Input
-ý-output
used
Input 5 Not used III
Input 6 Not used ý
Input 7 Not used III
Input 8 --l-Not used
iIII
III
10
I
II
Robot Interface
Trigger
Output 15-7- Wire Inching
Input 5Arc Detect Output
I
Input 6
I_Main
Error Output I
I
Input
Switch
Input 7I_ 24V Output
Wire Inching : Robot interface input used to provide wire feeding when not welding
Arc detect: Robot interface output used to indicate if the welding arc is on
Main Error: Robot interface output used to indicate a hardware failure in the power source
The three robot inputs were mainly used for returning authorization codes to
the robot controller as a response to the authorization requests issued by the same
controller via setting pre-determined combinations of robot outputs. The robot
program was generated off-line in such a way that the robot controller would issue an
authorization request and would wait for an acknowledgment code whenever a
programmed action should start. This would allow the master controller to supervise
the robot movements and the table controller to synchronize the table movements
with the robot. The authorization requests were coded in different combinations of
digital outputs and were programmed to be issued mainly during the pre-weld
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