Fanuc Motors

Motors with Fanuc ABS, incremental, and serial encoders are supported by the TI-5000JX. The current revision software supports 6 and 8 pole Fanuc motors on all encoders (that we know of) except the Alpha 16000i. Most Fanuc motors are 8 poles, so the number of poles defaults to 8 whenever a new type of Fanuc encoder is selected.

General Comments

Fanuc serial encoders are used only with Fanuc motors. There are significant differences in the various Fanuc models, but the test software takes that into account when displaying the results. The test procedure and commutation pulse patterns are basically the same for the various serial encoders.

Types Supported

The following list shows the Fanuc encoders that are currently supported by the TI-5000JX:

Pulsecoder A, B, B2, and C –

The Pulsecoder A, B, B2, and C are some of the earlier style encoders. They generally use 17 and 19 pin round MS type and DB15 type connectors.

Pulsecoder Alpha –

The Alpha series motors use the Alpha series encoders. They generally use 17 and 19 pin round MS type and the DB15 type connectors, but some of the built-in Alpha 8 encoders on smaller motors will use AMP D3100 two row connectors.

Fanuc has converted the Alpha encoders to a new, more compact package. These encoders commonly employ the 17 pin round MS connector, but it will be on a short cable that plugs into the encoder case via a 14 pin dual row header type connector.

Pulsecoder Alpha i –

A new series of Alpha i motors utilizes Alpha i encoders. These encoders look very similar to the Alpha encoders in the new package, and the data is very similar. However, they use a small 10 pin circular JAE connector.

Pulsecoder Beta –

The Beta series motors use built-in Beta encoders. The earlier motors employ the Beta I32B and A32B encoders. These encoders use DB15 connectors but also AMP D3100 two row connectors. BetaM motors use built-in Beta I64B and Beta A64B encoders. These encoders use the small 10 pin circular JAE connector.

ABS and Incremental –

The ABS and incremental encoders are tested like any other Generic Incremental Encoder.

Identification

The serial pulsecoders will normally have identification such as Pulsecoder A, Pulsecoder C, Pulsecoder Alpha A64, etc. on the label. Otherwise, the part number starting with A860 may have to be used to identify it by a reference to a Fanuc manual or a call to Fanuc.

The incremental and ABS encoders are easily identified due to the fact that they will have a 2000P, 3000P, etc. following the A860 part number. This is the number of pulses per revolution for the encoder, and it identifies it as and ABS or incremental. These encoders should be tested as Generic Incremental encoders.

Encoder Selection

Incremental and ABS Encoders

1. Click the Encoder Feedback radio button.
2. Select Generic Incremental Encoder from the Encoder Manufacturer dropdown menu.
3. The encoder type will default to AB Quadrature Count.
4. Click on the Enter Counts Per Revolution button. Multiply the number of pulses per revolution by 4 to get the number of counts/revolution. Fanuc incremental and ABS encoders will have a number such as 2000P, 3000P etc. after the A860 part number, and this is the number of pulses per revolution.

Serial Encoders

The Fanuc serial encoders require the following setup sequence:

1. Click on the Encoder Feedback radio button.
2. Select Fanuc from the Encoder Manufacturer dropdown menu.
3. Select the encoder type that you have from the Encoder Type dropdown menu.

The encoder types listed in the current software revision are shown in an earlier section.

Most Fanuc motors are 8 pole motors, and most of the encoder types specify 8 poles. There is a 6 pole selection available for the Pulsecoder A and the Pulsecoder Alpha A64. To determine the number of poles, apply a small voltage to 2 of the armature leads to lock the rotor, and then count the number of lockup positions to determine the number of pole pairs. For instance, if the rotor locks up in 4 different shaft positions, the motor has 4 pole pairs or 8 poles.

Testing

Fanuc Incremental and ABS encoders are tested as Generic Incremental Encoders using Data Display, Line Levels, Incremental Count Test, and Phase Test for a complete test. The Fanuc serial encoders (like most serial encoders) use only the Data Display and the Serial Count Test.

The forward armature direction for Fanuc motors is CCW looking at the drive shaft end.

Data Display

Data Display is the initial test, and it is started by default when Athena is started. When already in another test, it can be started by clicking on the Data Display button among the test buttons at the top of the display. Use it for the following:

1. Turn the encoder to ensure that the encoder is counting approximately the right number of counts
   per revolution.
2. Use the commutation display to check or set the feedback commutation alignment.
3. Check the encoder status for the following: ensure that the encoder is indexed, communicating
   properly with the tester, not reporting internal errors, correctly displaying overheat and battery
   alarms, and displaying the correct encoder ID (if ID is implemented).

The following sections describe information shown on the display.

Commutation

The Fanuc commutation gray code shown as C1 – C8 and the electrical angle can be used to check and set commutation using a static rotor lockup by applying a small lockup voltage to the stator windings. For a particular lockup polarity, the rotor will lock up in as many different positions as there are pole pairs but the gray code and electrical angle indications will be the same at each lockup position. The mechanical angle will be different at each lockup position (except for 2 pole motors where there is only one lockup position), so it is not as convenient to use for feedback alignment. See section 3.2 for a more detailed description of commutation alignment procedures.

The number of poles must be entered correctly for the electrical angle to be correct. In the case of the Fanuc motors, they will default to 8 unless one of the two 6 pole types is selected. The gray code and electrical angle are derived from a 10 bit commutation count in all serial pulsecoders except the Pulsecoder A, B, and B2 in which case they come from the position count. The mechanical angle comes from the position count for all Fanuc serial pulsecoders. The position count is absolute immediately upon power up only for the Pulsecoder A, B, and B2. On all others it is only absolute after the encoder is indexed, so dashes will appear in the Mechanical Angle box until the encoder is indexed. The Pulsecoder C does not display a mechanical angle.

The table below shows 4 different lockups that can be used to check or set commutation on motors with Fanuc serial encoders. The first two are commonly used with the gray codes but can be used with the electrical angle as well. The first procedure requires energizing all 3 armature lines. A slight wiggle of the shaft should result in the C8 indication toggling between 1 and 0. Likewise the second procedure in which only lines V and W are energized results in the C4 indication toggling when the shaft is wiggled.

The last two procedures can only be used with the electrical angle since they do not result in unique gray code patterns. It is easy to go from +U –V to +U –W just by moving the minus lead from V to W. This should cause the motor to jog 60 electrical degrees in the forward direction. Failure to move the correct number of degrees or in the correct direction would be an indication of a significant problem. Setting these angles within ±3 electrical degrees is normally quite sufficient.

The incremental and ABS encoders will be tested as Generic Incremental encoders, but their alignment
would follow the table below:

The entire gray code pattern is as follows:

It may be worth checking in some situations to verify that this pattern is taking place correctly.

Count

The Count frame displays the encoder count both as a decimal and hexadecimal number. Users will typically be interested in only the decimal count, but encoder repairmen and other advanced users may find the hexadecimal representation useful. On power up, this count will be zero for the Pulsecoder A and Alpha series when the encoder shaft is at the 9:00 position (i.e.: looking at the end of the shaft with the stamped model number under it, the arrow on the shaft will be pointing to the left). These encoders internally keep up with the count with respect to these references. The Pulsecoder C works differently in that its data reports the difference in the count from the previous reading to the present reading. Therefore, its zero reading will be referenced to its position at power-up. The TI-5000JX software accumulates these difference readings and maintains and reports a total count so that the result is a value similar to the total counts reported for the Pulsecoder A and Alpha series.

As mentioned previously, the count represents an absolute position on power up only for the Pulsecoder A, B, and B2. On other encoders, the count represents an absolute position only after the encoder is indexed. It does not represent an absolute position for the Pulsecoder C.

Always verify that the encoder count appears to change by the correct number of counts/rev while turning the encoder. If the count is not changing, then there is an encoder problem. As described in a later section, the Count Test may be performed to more accurately determine whether the correct number of counts per revolution is occurring, but this is an important initial evaluation.

Line States

The Pulsecoder C is the only supported serial pulsecoder for which a line state is indicated. The line state indicated is the Z or index line. This is not really an index line, like an incremental encoder, but an index bit that goes HI once per revolution. Even though it is not really a line state per se, the Z line state box is a convenient place to show it. The Pulsecoder C sets this bit HI momentarily when moved past the index position, so you will see the indicator flash HI momentarily. Unlike an incremental encoder, it will not stay HI if you stop right on the index position. The index pulse occurs when C1, C3, and C4 are HI and C2 is changing between LO and HI. This commutation indication will occur in as many different positions as there are pole pairs, but the index pulse will only occur in one of these positions. Note that this index indication is quite different from the Alpha and Beta series encoders. For the Alpha and Beta encoders, the count is index on the initial revolution after power up, while the Pulsecoder C is reporting an index position on every revolution.

Encoder Status

• INDEX – The INDEX box is disabled for the Pulsecoder A, B, and B2 because these encoders display the correct count on power up without indexing. It is also disabled for the Pulsecoder C because the TI-5000JX does not index for these encoders. All other serial pulsecoders must be indexed on power up unless they are absolute encoders which have been battery backed up. The absolute encoders will have an ‘A’ in their name while the incremental encoders will have an ‘I’. For instance the Fanuc Alpha I64 is an incremental encoder (incremental is Fanuc’s way of saying ‘not battery backed’ for serial encoders), so it will need to index on every power up. An Alpha A64 encoder is an absolute (absolute is Fanuc’s way of saying ‘battery backed’) so it will need to be indexed on power up only if it had not been connected to a battery. Always verify that the INDEX box changes from ALARM to OK within one revolution of the encoder.
• DATA - If no data is being sent from the encoder, NONE will be displayed in the DATA box. If the TI-5000JX and the encoder are communicating correctly, RECEIVING will be displayed in the DATA box. The cabling is the first thing to check if the encoder is not communicating, but it can also mean a component failure in the Pulsecoder.
• INTERNAL ERROR - The INTERNAL ERROR box will show ALARM if there is an internal error alarm and OK if there is not. Several bits in the data stream for the various Pulsecoders respond to the loss of an LED and the resulting counting problems. These bits are consolidated and reported under the INTERNAL box with ALARM if any are HI. If none of these bits are HI, then OK is displayed. Causes for alarms could be a malfunctioning LED, incorrect alignment of the optics, and other problems. Removal of the board in the Pulsecoder is likely to cause some alignment problems.
• BATTERY - The BATTERY box will show ALARM if there is a battery error alarm and OK if there is not. It is often possible to alternately connect and disconnect battery voltages to the encoder to verify that this bit is working properly. This field is disabled for Alpha and Beta Pulsecoder I (incremental) encoders and the Pulsecoder C because they do not have battery backup capability. The remaining absolute pulsecoders will use this. The Pulsecoders with battery capability should show ALARM in this column if the voltage on the +6VA and 0VA lines is less than approximately 4.6 VDC. If the voltage is above approximately 4.6 VDC, the display should show OK. Many Fanuc encoders use a separate battery cable that is not part of the encoder signal harness. However, some encoders use lines that are part of the signal harness for the battery. The Fanuc serial cables (TI-5004, TI-5006, and TI-5007) bring out the battery line for easy connection. Using a clip lead to jumper the battery wire to J1 pin 1 (+5V) on the TI-5000JX is a good way to supply battery voltage. When this is done and the display changes to OK, sometimes it is necessary to connect the clip lead to J1 pin 2 (GND) in order to make it display ALARM again. Download cable sheets from the Customer Page at http://www.mitchell-electronics.com for cable pinouts and wiring details.
• OVERHEAT - The OVERHEAT box will show ALARM if there is an overheat error alarm and OK if there is not. It is often possible to alternately connect and disconnect thermal lines to the encoder to verify that this bit is working properly This field may not be in effect for all serial encoders. Thermal contacts inside the Pulsecoder complete a circuit to ground when temperatures are within range. When temperatures become excessive, the contacts open, and the overheat bit is transmitted with the data. The Pulsecoders with the DB15 connectors indicate only their own temperature and do not loop through the motor. Pulsecoders with the circular connectors however, bring this circuit out on the BRN and RED wires (which do not go to the circular connector). In a normal installation these wires are connected through other contacts such as motor overload contacts. These wires can be connected together during testing. When connected together, the Pulsecoder should not indicate an overheat condition (providing it is not overheated) with an OK display. If these wires are disconnected from each other, the OVERHEAT box should indicate ALARM.
  The newer Alpha i and Beta i encoders connect to the motor using two round brass contacts on the face of the encoder (near the shaft coupling). This of course means that the encoder must be mounted on the motor so that the motor overheat contacts mate with these contacts on the encoder. Unlike previous model pulsecoders, these newer style encoders are apparently not looking for a contact closure but are reading a thermistor or some similar device in the motor. If these contacts are shorted, the ALARM indication will not change to OK (and stay that way). However, if a resistor from around 5K to 50K ohms is connected to these contacts, the display will change to OK. A 10K resistor is a commonly available value, and it is probably a good value to use for testing these encoders.
• ENCODER ID – There is no encoder ID support for Fanuc serial encoders.

Count Test

The Count Test can be started by clicking on the Count Test button among the test buttons at the top of the display. The Count Test it will verify that the encoder is incrementing the correct number of counts per
revolution. The Count Test for the Fanuc encoders is not significantly different from that for other encoders, so please refer to the general information on the count test in Section 2.2.2 for further details. The number of bits tested by the Stuck Bit Test varies depending upon the particular model. Encoders with greater than a 16 bit count per revolution will test bit0 to bit15 for activity. Others will test as many bits as are used in the count for one revolution.