Mesa 5i20 + 7i48 + multiplexing

I compiled the master version of EMC2 (2.5.0~pre) for my initial tests with Mesa hardware. I followed instructions from: "http://wiki.linuxcnc.org/emcinfo.pl?Installing_EMC2". After I got the EMC2 up and running I started to tweak the .hal and .ini -files.

In the .hal file I added five servo threads and I also added servo related information for each axis.

In the .ini file I used SV12IM_2x7I48_72.BIT firmware for the 5i20 board. I told also that I have five axis (analog servo amps) that I need to control. For initial testing I'm using AXIS-display program (gui) showing information from all five axis. I still have to fill in correct values for each servo-axis, but for initial testing I left values to default.

After I got everything configured correctly (AXIS actually showed all five axis) I connected three servo motors (just encoders) to the 7i48 board. I connected them to ports:1,2 and 5 to see how the multiplexing thing would work (7i48 provides 6-analog servo-interface).

I took a picture of the screen while rotating the axes of the motors. EMC2 actually understood the input that the encoders were giving, multiplexing seems to work quite nicely. Now I have to connect also the servo amps to the 7i48 board to see if I can actually control my AC-servo motors.

Panasonic AC Servo Motors

These are AC servo motors that I'm planning to use in my milling machine upgrade. These are Panasonic units with a model number: MSM022A2UE. I couldn't find exact datasheet for these  units but the nearest one will have to do. The power rating is 200W and the encoders give 2500ppr.

I purchased these motors without knowing that these motors are not providing regular hall-feedback for the amplifier. The three hall signals (A,B,C) are encoded to a two wire output. Because my servo amplifier needs three hall signals for working properly I decided to take a closer look at the encoder.

I traced the encoder signal "R" (=encoded hall signal) to one microchip. I attached my old oscilloscope to different pins on the chip and rotated the motor shaft to see whats happening inside the circuitry. I found three pins that were giving promising outputs at 5v voltage level.

I connected the three motor wires together with three 10kohm resistors and attached one channel of oscilloscope to motor terminal A with respect to the "Wye" neutral. I started to turn the motor shaft with external power source (cordless drill) and used the second oscilloscope probe to determine the hall signal that is in "phase" with the generated voltage from terminal A. Now I was able to measure the signals from the motor coils and find out the correct phasing for the three hall-signals.

After I was convinced that I got it all right I connected the motor to my servo amp and turned the power on. The motor started to turn just as it should, obviously I had found the correct phasing. The next job is to connect these amps/ motors with the Mesa Electronics 7I48 interface.

KEBA HT 401/NCO pendant

This is a HT401-222/NCO-4/0 teach pendant from KEBA. It includes:

- 40 membrane keys with one 2-color led assigned to each of them
- LED-backlight LCD with 4x16 characters.
- Two override potentiometers
- Electronic handwheel (MPG), 100ppr.
- Enabling switches
- Emergency Stop Switch

Communication interface is based on RS-232-C and the internal configuration is programmed to a Hitachi H8/3002 microprocessor. I'll see if I can get this configured correctly for a EMC2 use, otherwise I'll just connect the necessary buttons and MPG to the MESA 5I20 I/O-pins.

Mesa Electronics 5I20 fpga-card and 7I48 6-channel analog interface

5I20 is a programmable pci-card, providing 72 I/O lines. 5I20 has three 50-pin connectors for I/O lines; one will be used for connecting the 7I48 analog interface card to the system, one will be used for the pendant connections and the last will serve as a machine connector (E-stop+limit switches...). I'll be using Linux EMC2 for controlling my machine and I'll have to learn some basic stuff of machine configuration files (.ini and .hal) to get everything up and running.

7I48 is a 6-channel analog interface for operation with 5I20 for motion control application. A single I/O connector of 5I20 will support six axis interface with the help of multiplexing. The 7I48 takes pwm signal from 5I20 and converts them to +- 10V analog output voltage for driving analog servo amps. In my case
5 x Aerotech BA20-160.

I purchased these cards from:
http://www.duzi.cz/shop_cnc/index.php?main_page=index&cPath=1

Brushless servo amplifier

I have recently acquired five brushless servo amps (eBay), units are manufactured by Aerotech,Inc. I'll be using these for upgrading my CNC-mill from open loop (stepper) system to a closed loop one.

 Model number is BA20-160, it means peak output current rating of 20 amps and output voltage in the range: 80-160V. With some modifications to the power supply of the amp the output voltage can be anything between 0V to 320V. I have already tested one amp with a 40VDC servo motor. These units can be configured to drive brush or brushless servo motors.

 One amp will be used for driving spindle motor (DC) and four amps will be used for driving AC servo motors (X Y Z A).