Generic Incremental Encoders

Generic Encoder feedback is a special case. Rather than try to categorize or list all the manufacturers of various incremental encoder setups, incremental encoders are simply listed as a generic type.

Generic Encoder Feedback provides a general method of running incremental encoder feedback motors with line to neutral timing in much the same way as with Resolver feedback. The user must enter certain timing information so that the TI-3000JX knows how to deal with the specific motor. To use this selection, the encoder must have A, B, and Z pulses, and the number of counts per revolution cannot be greater than 32,768. Serial encoders which also have A, B, and Z lines can be run in this manner, but strictly serial encoders cannot.

Often these motors are AC servo motors that use the encoder count for feedback after the count is indexed by the Z pulse. There are various ways these motors receive information for starting (before the count is indexed). The most common methods are to provide U, V, and W commutation pulses, or to provide an absolute serial count position on startup. Both of these methods are represented among the motors supported under the Yaskawa and Sanyo Denki options.

Generally speaking, if you have purchased a specific option (such as Yaskawa or Sanyo Denki), it is better to run the motor as a manufacturer specific selection. It will be quicker because you do not have to enter any information about the motor or feedback. In cases where it uses serial data or commutation pulses for starting, it will provide a more realistic test of the motor operation. When run as Generic Encoder feedback, the TI-3000JX uses only the count from the A, B, and Z pulses for commutation and nothing more. Motors run in this manner must be turned by hand before starting in order to index the encoder, whereas motors run under the manufacturer specific selections will generally be self-starting

Setup

The FBK MFG key must be pressed until the top line of the display shows Generic Enc. The FBK TYPE key has no function for the Generic Incremental Encoder Setup.

The TI-3000JX needs 4 pieces of information to run the incremental encoder based motor:

1. The number of poles of the motor.
2. The counts per revolution of the encoder
3. Whether phase B must lead phase A (D>B) or phase A must lead phase B (D>A) in order for the forward direction of the encoder to be the same as the armature phase forward direction.
4. The encoder electrical angle when the rotor is locked using a +U –V lockup polarity (this can be accurately read from the display only after the first 3 items have been correctly entered).

This information can be found quickly and easily by a simple procedure. The information can then be entered into the TI-3000JX setup. All information of this type can be cataloged, and simply entered into the TI-3000JX the next time a motor of the same type is used. The 10 step procedure is described below. On the page following the procedure a form is shown that can be used to record the motor information during the procedure. You may wish to make copies of this page for recording your information.

1. Connect the encoder leads to the TI-3000JX encoder terminal block, J1 in the manner suggested by the motor manufacturer:
   
   
   
   Note: Please see the section on incremental encoders for more information. 
   
   
2. Power up the TI-3000JX and select Generic Enc by pressing the FBK MFG key. When this selection has been made, press the DEBUG key to go into Debug Mode. The display will show “Debug – Manually Rotate to Index”. At this point, manually rotate the motor shaft (normally 2 revolutions or so) until this message disappears. If it fails to do so, press the STOP key, the press the DEBUG key to retry. When the message disappears, it means that the TI-3000JX has detected the index pulse, and it has zeroed the count and measured the number of Counts/Rev of the encoder. Read the number of Counts/Rev from the bottom line of the encoder (example: C06000 means 6,000 counts/rev). You may already know the number of counts/rev for the encoder due to testing using the TI-5000JX. However you may have found the number of counts/rev, record the counts/rev on your worksheet. Remember that the maximum counts/rev is 32,768.
   
   
3. With the armature disconnected from the amplifier, connect a low voltage (around 5 volts, preferably adjustable from a small bench power supply) with + to the U and - to the V armature leads (or +A, -B, or however they are designated). The motor should move to a position where it locks up.
   
   Note: If you do not have information on armature pinouts, make up your own assignments and proceed. Enter the pinout designations on the worksheet. 
   
   
4. Slowly rotate the motor by hand through a full revolution and note the number of times it locks up in one rotation. Multiply that number by 2 and enter it as the number of poles on the worksheet.
   
   
5. Visually note the lockup position. Turn off the power supply, and leaving the + power supply lead on U, move the - lead from V to W. Turn the power supply back on, and the motor should move a small amount either CW or CCW. Note this direction on the worksheet as the forward armature direction. Also notice whether the encoder count increased or decreased as the motor moved in the forward direction. The TI-3000JX must be set so that the count increases in the forward direction.
   
   
6. Most of the information is now available to enter into the TI-3000JX. Some of it must be entered at this time so that the lockup angle can be read correctly in later steps. Press the STOP key to exit Debug Mode. Then press the SETUP key, and a data entry screen will appear. The cursor will be on the field for the number of poles. It will read either 2 as the default or the last number entered. Each time the EDIT key is pressed, the number will increment to a new number of poles. After reading 36, it will return to 2. Press EDIT until it reads the number of poles indicated on the worksheet. With the correct number of poles showing, press the ENTER key, and the cursor will move to the Counts/rev field which begins with “C>” and ends with a 5 digit number (leading zeroes included). It will read the last number entered. Key in 5 digits (including leading zeroes) to enter the number of counts/rev recorded on the worksheet. After the 5th digit is entered the cursor will jump to the direction field.
   
   The direction field begins with “D>” and ends with either A or B. A means that the encoder produces a positive count when the A pulse leads the B pulse. Conversely, a B means the positive count occurs when B leads A. Each time the EDIT key is pressed, the display will toggle from A to B or vice versa. If in step 5 the encoder angle was increasing when the motor turned in the forward direction, then leave the setting alone as it is correct. If the encoder angle was decreasing when the motor turned in the forward direction, then toggle to the alternate setting to reverse the encoder count direction. Record on the worksheet the setting that makes the encoder angle increase when the motor is rotated in the forward direction. Press the SETUP key to exit Setup Mode.
   
   
7. Again press the DEBUG key to go into Debug Mode. Rotate the motor shaft (normally 2 revolutions or so) until the message prompt to rotate, disappears. If it fails to do so, press the STOP key, then again press the DEBUG key to retry. Verify that the displayed angle increases when the motor is rotated in the forward direction. If it does not, then repeat the direction setting in step 6 until it does.
   
   Again apply a DC voltage + to U and - to V. Move the motor through one rotation in the forward direction, and record each lockup angle. There should be one lockup position for each pole pair. For instance, a 2 pole motor will have one position, while an 8 pole will have 4 lockup positions. In the Generic Encoder case, the angles will be electrical angles, so each lockup position should show approximately the same angle (normally no more than +/- 5 degrees different). If the angles are significantly different, check to see that you have entered the correct number of counts/rev for the encoder and correct number of poles for the motor.
   
   
8. The remaining information is now available to enter into the TI-3000JX. As in step 5, press the STOP key and then the SETUP key to enter Setup Mode. The cursor will be on the field for the number of poles. Press the ENTER key and the cursor will advance to the counts/rev field, followed by the direction field, and finally to the Angle field. The Angle field will read either 000 as the default or the last angle entered. Key in 3 digits to enter the number of degrees recorded on the worksheet in the lockup data. After the 3rd digit is entered the cursor will jump back to the Poles field. Note: Angles must be entered as 3 digits with leading zeroes if necessary. For example, 30 degrees must be entered as 030. Review the number of poles, counts/rev, direction, and angle data showing on the display. If any are incorrect, use the ENTER key to move to that field and correct the data as described above. When the data is correct, press the SETUP key to exit the resolver setup menu. The 2nd line of the display will show the information as follows:
   
   Pp Dd Addd L+-*                 where: p = number of poles
                                                           d = Direction, A or B
                                                           ddd = lockup angle
   
   
   For instance, if it is a 4 pole motor with a B leading A encoder direction (for forward rotation) that locks up at 150 degrees, the display will show: P4 DB A150 L+-*

Debugging

Debugging is a quick and essential step that must be accomplished before trying to run the motor. If there are any problems in the setup, correct debugging should find them. If the correct setup has not been verified by debugging, there is nothing to be accomplished by attempting to run the motor.

Section 2.2.3 provides general information about debugging the TI-3000JX setup. You will want to be familiar with that material.

When you believe that the TI-3000JX is properly set up (as described in the previous section), perform the following steps to debug the setup:

1. Press the DEBUG key to enter DEBUG mode.
   
   
2. Rotate the shaft and verify that the encoder angle moves smoothly through the entire range of angles from 0 to 359 degrees. It should move through that range the same number of times as the number of motor pole pairs (2 poles – 1 time, 8 poles – 4 times, etc.).
   
   
3. Verify that the armature leads are not connected to the drive. From the lockup power supply, connect the + lead to the U phase and the – lead to the V phase
   
   
4. Switch on the lockup power supply. The angle reading should be very close to the lockup angle that
   you recorded on your worksheet. For motor poles greater than 2, there will be multiple lockup positions, but the angles should be the same within 2 or 3 degrees.
   
   
5. On the TI-3000JX display, you should see V = H and W = L. When you wiggle the shaft slightly, you
   should see U change or toggle between H and L. This is very important. If this does not happen, the
   motor cannot run properly, and you have a mistake in your setup that must be corrected.
   
   
6. Switch off the lockup power supply and move the – lead from phase V to phase W. This will provide a valuable cross-check for verifying proper operation.
   
   
7. Switch on the power supply and note which way the motor jogs. This should agree with the forward direction you noted on your worksheet.
   
   
8. Read the angle from the TI-3000JX display. If it is greater than the angle you read with the +U –V lockup (providing the angle did not move through zero), the encoder and armature rotation are the same. If the displayed angle is less than the angle you read with the +U –V lockup (providing the angle did not move through zero), the encoder and armature rotation are opposite. You probably need to change to the opposite encoder direction in your setup (for instance change to D>B if you were set on D>A).
   
   
9. On the TI-3000JX display, you should see U = L and V = H. When you wiggle the shaft slightly, you should see W change or toggle between H and L. This is very important. If this does not happen, the motor cannot run properly, and you have a mistake in your setup that must be corrected.

Those specific setup checks should help insure that your incremental encoder motor will run correctly. For more general information on debugging your setup, see Section 2.2.3.

Running

Section 2.2.4 provides general information about running motors with the TI-3000JX. You will want to be familiar with that material.

Section 2.2.5 provides safety information to be observed when running motors with the TI-3000JX. Please read this section carefully and exercise all safety considerations

Encoders with 5 volt square wave signals usually do not have noise problems, although the some of the
suggestions below (such as the case ground line with the power leads) are good advice for running any
motor.

Encoders with 1 V p-p signals, such as the Heidenhain ERN1387 encoder often used on Siemens motors, are more likely to have noise problems due to the low level signals. Using the TI-5101 1 V p-p Adapter module with these encoders can reduce noise problems. The differential amplifiers in the module tend to cancel the noise and amplify the desired signal to a higher level.

If you use the TI-5101 module with the TI-3000JX, it is recommended that you set the module dipswitches to OPEN to guarantee that the module will output the A, B, and Z channel signals rather than C and D channel signals. When the module is used with the TI-5000JX, the dipswitches should be set back to CLOSED in order to look at the C and D channels.

Here are some further points to help reduce noise:

1. Make sure that you have a ground continuous from the motor body to the body of the drive. The drive cable has a G pin on it that goes to the drive body. The motor usually has a ground pin on the power connector. Make sure you make that connection.
2. Sometimes a shielded cable for the armature leads will help.
3. Sometimes a shielded cable for the encoder leads will help.
4. Try to keep the power leads and feedback leads as far apart as possible.