The project:
Fixture for checking long steal pins (.250" to 1.0" Dia. 4" to 24" long)
The PLC:
AD D06 with 3 H0-CTRIO cards to control 3 stepping motors (X,Y and A axis)
X and Y axis have linear scales as feedback.
Data logging:
Third party device that takes AB quadrature inputs to save X,Y and Dia. data to a spreadsheet, this device is controlled by the PLC as to when and what data to log by PLC I/Os.
The problem:
The system made it through the design phase with direct feedback from the customer, I was sent to the customer to assemble the system for finale checkout, As the system was being Demoed to a management team it was noted that the A axis (Rotary axis) data was not sent to the spreadsheet for collection and that it most be, I was also told that an encoder could not be installed on the A axis drive for environmental reasons.
Head scratching and missed flight starts here.
Fix tried #1:
Because I had one slot open in the PLC I installed one more H0-CTRIO card and configured it as two counters on input A and B, I then setup the preset tables to output Y0 when A=1 and output Y1 when B=2, I then put the step output to the stepper motor drive from the A axis as the input to A and B counters of the 4th CTRIO card with the hope of generating a synthetic A/B quadrature signal that the Data Logger could read. while it did work, but only if velocity stayed the same. I could tweak the data logger's count ratio for the input to read right at as 45 deg. but if I change to 90 deg. it would be off
by over 10 deg.
More head scratching.
I then got on the internet to see if someone made a Step/Direction to A/B Quadrature converter, and as it turned out someone did.
http://irtfweb.ifa.hawaii.edu/~tcs3/tcs3/Design/Data_Sheets/SE_FIOE/equad.pdf
I feed this device the Y0 and Y1 outputs of the A axis H0-CTRIO card and the Output of it to the data logging devices A/B inputs. it worked sweet!
I made my next flight home.
While it does not given true feedback, I can see a number of uses for it.
and at $100US it can be a low cost fix.
Tommy
Fixture for checking long steal pins (.250" to 1.0" Dia. 4" to 24" long)
The PLC:
AD D06 with 3 H0-CTRIO cards to control 3 stepping motors (X,Y and A axis)
X and Y axis have linear scales as feedback.
Data logging:
Third party device that takes AB quadrature inputs to save X,Y and Dia. data to a spreadsheet, this device is controlled by the PLC as to when and what data to log by PLC I/Os.
The problem:
The system made it through the design phase with direct feedback from the customer, I was sent to the customer to assemble the system for finale checkout, As the system was being Demoed to a management team it was noted that the A axis (Rotary axis) data was not sent to the spreadsheet for collection and that it most be, I was also told that an encoder could not be installed on the A axis drive for environmental reasons.
Head scratching and missed flight starts here.
Fix tried #1:
Because I had one slot open in the PLC I installed one more H0-CTRIO card and configured it as two counters on input A and B, I then setup the preset tables to output Y0 when A=1 and output Y1 when B=2, I then put the step output to the stepper motor drive from the A axis as the input to A and B counters of the 4th CTRIO card with the hope of generating a synthetic A/B quadrature signal that the Data Logger could read. while it did work, but only if velocity stayed the same. I could tweak the data logger's count ratio for the input to read right at as 45 deg. but if I change to 90 deg. it would be off
by over 10 deg.
More head scratching.
I then got on the internet to see if someone made a Step/Direction to A/B Quadrature converter, and as it turned out someone did.
http://irtfweb.ifa.hawaii.edu/~tcs3/tcs3/Design/Data_Sheets/SE_FIOE/equad.pdf
I feed this device the Y0 and Y1 outputs of the A axis H0-CTRIO card and the Output of it to the data logging devices A/B inputs. it worked sweet!
I made my next flight home.
While it does not given true feedback, I can see a number of uses for it.
and at $100US it can be a low cost fix.
Tommy
