8.4 Rotary Servo Control Box - Troubleshooting

The display shows the program and mode for the rotary unit. The display consists of 4 lines with up to 80 characters per line. Data displayed includes:

• Position (Spindle)
• Step Size (Angle)
• Feed Rate
• Loop Count
• G-Code
• Current Step Number (Step numbers 1 to 99 are available)
• Any Start-Up Errors or Alarms

The display highlights a single step of the program on display line 2. Press DISPLAY SCAN right arrow to scan sideways and see all the information for a single step, loops from left to right at the end of the row. Press STEP SCAN up arrow to display the previous step; press STEP SCAN down arrow to display the next step. You can scan to anywhere in the program with these keys. If a new number is entered in that position, the number is stored when scanned to another position or returned to Run mode.

Every step (or block) contains several pieces of information that are necessary for the program and are displayed simultaneously. The data is preceded by a letter(s) to indicate what type of information is displayed.

Each time you press the DISPLAY SCAN right arrow, the display cycles to the next register; that is, Position - Step Size - Feed Rate - Loop Count - G-Code - Position - etc. In Run mode, the DISPLAY SCAN right arrow button selects among any of these five displays. In Program mode, all of these but the Position may be displayed.

A set of self tests are run when the control is turned on and the results may indicate a control fault. These are displayed on the Alarm: 4th line.

NOTE:  Intermittent low voltage errors or power failures may be the result of inadequate power to the controller. Use short, heavy-duty extension cords. Make sure that the supplied power is a minimum of 15 amps at the plug.

Any time the servo (motor) is turned off, a reason code is displayed on the Alarm: 4th line, along with the following codes.

An A or B may precede the code for TRT units. This is the reference to the axis that caused the fault.

Troubleshooting a Working Interface on a CNC

If there are problems, try to isolate the problem by checking the Servo Control and the mill separately. There are only two signals and each one can be checked separately from the other. If the rotary unit stops indexing because of an interface problem, follow these simple checks:

• Check the Servo Control remote input alone
• Check the CNC cable interface alone
• Check the Servo Control and the mill together

Check Servo Control Remote Input Alone

To check the Servo Control remote input:

1. Disconnect the remote cable from the back of the controller.
2. Set the control to index a single step of 90°�.
3. Connect a continuity tester or a voltmeter (a digital meter may not be fast enough to sample the brief pulse) set for low ohms across pins 1 and 2; they are marked on the rear of the control as FINISH SIGNAL.
4. It must show an open circuit, otherwise check relay Parameter 1 (should be 1) and Parameter 2 (should be 0). The relay must show an open circuit with the control turned off, otherwise the relay is defective.
5. Use a jumper wire to short pins 3 and 4 together, they are marked on the rear of the control as CYCLE START.
6. The unit must index, and at the end of the index, the voltmeter should deflect briefly toward low ohms or continuity. If this works as described, the problem is NOT in the rotary control, but may be the interface cable or mill.

Check The CNC Cable Interface Alone

To check the CNC cable interface:

Check the signals from the CNC using your voltmeter.

NOTE: The pin orientation is reversed.

Execute an M function from the mill to rotate.

The mill beacon light should come on (green) and stay on.

Use the meter and check continuity across the CYCLE START pins 3 and 4. Try not to short the test leads and pins against the shield of the male plug.

note: Some mills may have a +12 to +24 volt signal on pin 4 to activate a rotary unit. Check if there is voltage between pin 4 and the ground, if the continuity test fails, this is also a valid CYCLE START signal. If there is voltage present on Pin 4, a Haas interface box must be used (Part # IB). Contact your dealer if there are questions on how to use the interface box.

To check the CYCLE FINISH signal, use a voltmeter test probe to short together pins 1 and 2 on the mill cable.

The mill beacon light should turn off.

Result: 

If the above tests pass, there is a valid signals coming from the mill.

Check Servo Control And Mill Together

To check the Servo Control and mill:

1. Reset the mill by pressing RESET or turn it off by pressing POWER OFF.

2. Connect the remote cable, then turn both the Servo Control and mill on.

Once connected, the rotary unit should remain idle. If the rotary unit moves, the CYCLE START signal from the mill is shorted.

3. If it remains idle, execute or MDI an M function from the mill to index.

Do not index from the program unless using single-block. If the rotary unit does not move, the mill is not outputting a signal or there is a break in the cable.

If the Servo Control indexes properly, ensure that the mill beacon light goes out at the end of the index. If the light does not go out, the CYCLE FINISH signal is not returning to the mill. This could be an open wire in the remote cable, or a problem in cables that connect to the CNC.

4.  If the unit works only in single block, but not in the Run mode, there may be a timing problem involving two M functions, or a simultaneous milling problem. Review the section on simultaneous milling. If there are two M functions, separate them with a dwell of ¼ second.