B&R 8AC120.60-1 | EnDat 2.1 Encoder Interface Module

Product Introduction (Anti-Template)

When a servo drive loses reliable motor feedback, the drive itself may still power up normally while position control becomes unusable. B&R 8AC120.60-1 is an ACOPOS plug-in encoder interface module designed for EnDat 2.1 encoders and also capable of evaluating simple sinusoidal incremental encoder signals.

Installed in slots 2, 3, or 4 of a compatible ACOPOS drive, the module provides encoder monitoring, a nominal 5 V encoder supply, and differential sine/cosine signal processing. The maximum specified encoder cable length is 50 m.

Key Technical Specifications

B&R specifically describes 8AC120.60-1 as an EnDat 2.1 encoder interface for ACOPOS servo drives, with support for simple incremental encoders using sinusoidal input signals.

The encoder supply is nominally 5 V with a 250 mA load capability. The encoder interface is not electrically isolated from the ACOPOS drive, which is an important consideration when troubleshooting grounding and feedback faults.

Field Application & Technical Pitfalls (The Engineer’s Guide)

The 8AC120.60-1 is a feedback component, so its failure usually shows up as a motion-control problem rather than a simple module fault.

1. Servo motor position feedback
   In ACOPOS motion systems, the encoder provides the drive with position information required for accurate motor control. An unstable feedback signal can produce positioning errors, drive faults, or unexpected motion behavior.
2. EnDat encoder applications
   The module supports EnDat 2.1 encoders, including single-turn and multi-turn variants listed by B&R. Different encoder types have different power-consumption requirements, so the encoder code should be checked before replacement.
3. Sinusoidal incremental encoder applications
   The module can also process differential sine/cosine signals. The specified signal bandwidth reaches 300 kHz at -3 dB and 400 kHz at -5 dB.

Three replacement pitfalls deserve particular attention:

• Encoder protocol mismatch: Do not assume that every feedback encoder is compatible simply because it uses a 15-pin connector. EnDat 2.1 and sinusoidal incremental feedback are different signal architectures.
• Cable length and signal quality: The maximum specified encoder cable length is 50 m. Long cables, poor shielding, or incorrect termination can create intermittent feedback errors that look like a defective interface module.
• Encoder supply loading: The module provides approximately 5 V with a 250 mA load capability. Check the encoder’s actual consumption before connecting a replacement, particularly when the machine uses a less common multi-turn encoder.

Do not disconnect or reconnect the encoder while the servo drive is energized. Feedback connectors carry both signal and encoder-supply circuits; an accidental short during connection can damage the interface.

Lesson learned: A machine shows intermittent following errors after an encoder replacement, so the technician suspects the 8AC120.60-1. The actual problem turns out to be a poorly shielded feedback cable running alongside a high-current motor cable. The module was healthy; the installation was creating noise on the feedback signal.

Quality Control (QC) SOP & Transparency

1. Inbound Verification
   • Verify the exact B&R material number 8AC120.60-1.
   • Check the module label, B&R identification code, connectors, and housing.
   • Inspect the 15-pin DSUB connector for bent or recessed contacts.
   • Check for oxidation, PCB contamination, cracked components, or evidence of previous repair.
   • Confirm that the unit corresponds to the ACOPOS encoder-interface version rather than another plug-in module.
2. Live Rig Testing
   • Install the module in a compatible ACOPOS servo drive test environment.
   • Verify correct module recognition and startup status.
   • Connect a compatible EnDat 2.1 encoder where available.
   • Check encoder identification, feedback stability, and monitoring functions.
   • Where applicable, test sinusoidal incremental feedback using an appropriate signal source.
3. Parameter Testing
   • Verify the nominal 5 V encoder supply.
   • Check the 250 mA encoder-supply capability under a controlled load.
   • Test differential sine/cosine signal reception.
   • Verify reference-input behavior.
   • Check RS485 communication at the specified 625 kbaud rate where applicable.
   • Monitor for intermittent encoder alarms or loss of feedback.
4. Final QA & Packaging
   • Record the exact model, identification code, and test results.
   • Apply a QC-passed identification label after testing.
   • Place the module in anti-static packaging.
   • Protect the DSUB connector from mechanical impact.
   • Provide the applicable test record and a 12-month warranty under the agreed warranty terms.

Frequently Asked Questions (FAQ)

Q1. What is B&R 8AC120.60-1?
It is an ACOPOS plug-in encoder interface module for EnDat 2.1 encoders and compatible sinusoidal incremental encoders. It provides the feedback interface between the encoder and ACOPOS servo drive.

Q2. Which ACOPOS slots accept this module?
B&R specifies slots 2, 3, and 4 for the 8AC120.60-1.

Q3. What encoder protocol does it support?
Its primary interface is EnDat 2.1. B&R also specifies compatibility with simple incremental encoders using sinusoidal input signals.

Q4. What encoder supply voltage does it provide?
The documented encoder supply is typically 5 V, with a load capability of 250 mA.

Q5. Can I use a 100 m encoder cable with this module?
No—not as a normal specification-compliant installation. B&R specifies a maximum encoder cable length of 50 m. If the existing machine exceeds that distance, the complete feedback architecture should be reviewed rather than simply installing a longer cable.

Q6. Is the encoder electrically isolated from the ACOPOS drive?
No. B&R specifies no electrical isolation between the encoder and ACOPOS. Grounding, shielding, and cable routing therefore deserve particular attention in noisy servo installations.

Q7. What warranty is available?
A 12-month warranty can be provided under the agreed supply terms. For compatibility, the safest approach is to confirm the existing ACOPOS drive model, encoder model, and feedback protocol before ordering the replacement.