PCI 7390 - MCA 7790 - Panasonic Motors

Question

Hello,
We have bought the PCI 7390 and MCA 7790 boards in order to control Panasonic Motors. Specifically, we want to control the MADDT1207 and MADDT1207N servo drives for MINAS A4/A4N motors.
Our firs trouble is with the MADDT1207N servo drive, wich does not have direct conectivity with the MCA 7790 board. We have a 50 pin SCSI cable to connect the MADDT1207 with the MCA 7790, and it works more or less ok, but the MADDT1207N has a 37 pin connector instead of 50 pin. My question is, is there any way to connect them. Does National Instruments sell a special cable for this?
I use Measurment & Automation to test the boards with the MADDT1207 servo drives (the 50 pins one), and after some time to configure both, the MADDT1207 and the Measurment & Automation program, I am able to move the motor. Ten points for NI!! Its quite easy if you take some considerations. But what I am not able to, is to get the encoder data correctly. I know this data is transferred by the OA, OB and OZ differential signals. If I go to Measurment & Automation->NI Motion Devices->PCI 7390->1D interactive->Advanced Tab->Advanced Data group box, there is a field that says Encoder, and it ontly changes between 0 and 1, so I believe the data is being transferred, but the PCI 7390 does not understand MADDT1207. Looking at the panasonics manual, I realized that each differential (OA, OB, and OZ) pair must be terminated with a 330 ohm parallel resistor. This is my second question, does anybody know if I have to put this resistor? I measured with the multimeter and the pair is terminated with high impedance (no resistor). I tried to put a 330 ohm resistor in the MCA 7790 board (just between the connector pins), but nothing changed. I know the resistor must be at the end of the pair, but I would not like to solder the resistors in the PCI board if its not needed.
In the Encoder Settings in Measurment & Automation->Default 7390 Settings->Axis 1, I have disabled the Filter Fequency field, I put 10000 counts per revolution, and I tried with several combinations of Polarities and Index References Criteria.
In the Servo parameters I have:
44 (number of output pulse ratio) = 2500 (counts per revolution)
45 (denominator of output pulse ration) = 0 (wich means x4 (= 10000), is used)
46 Pulse output logic inversion = 0 (no inversion)
47 Z-phase of external scale set up = 0 (Z-phase output of external scale becomes invalid)
Any ideas? Does anybode succeeded with the encoder?
Thanks in advance

Answer 1

Hello everybody,
After a month searching the problem, finally I found it:
My new 50pin SCSI cable is broken: the pins 48 and 49, corresponding to the encoder signals OB+ and OB- were shorted. The cable has a label with the reference:
NATIONAL INSTRUMENTS 194604A-02, 50 POS MDR, 0636 12506
I used a standard 50pin SCSI cable and it worked fine.