Resolving Yaskawa SGD7S EtherCAT Recognition Failure in LabVIEW

Affected hardware: Yaskawa Sigma-7 SGD7S series SERVOPACKs with the F0 EtherCAT designator, including SGD7S-R90F0A0A (90 W class, 200 V input). Applies to engineers who attempt to connect a Sigma-7 EtherCAT drive directly to a Windows PC, NI CompactRIO, or NI PXI controller running LabVIEW 2016/2019/2021 without first installing an EtherCAT master stack.

Symptom summary: The Cat5e cable lights both link LEDs. The drive's front panel reads A.000 (no communication) or one of the A.E2x error codes. NI MAX, the LabVIEW Real-Time project, and any external EtherCAT scanner report zero slaves. The drive does not respond to ARP, ICMP, or Modbus/TCP poll requests because it is an EtherCAT slave only.

Root cause in one sentence: EtherCAT is a strictly master-slave deterministic fieldbus; the SGD7S-F0 is a slave device and cannot establish a session without a master on the wire, and desktop LabVIEW on a Windows PC is not an EtherCAT master.

1. Architecture Background: Why a Direct PC Connection Cannot Work

EtherCAT (Ethernet for Control Automation Technology) is a deterministic real-time fieldbus developed by Beckhoff Automation and maintained by the EtherCAT Technology Group (ETG). Unlike TCP/IP Ethernet, EtherCAT does not use IP addresses, ARP, or standard packet exchange. Instead, the master node sends a single Ethernet frame that passes through each slave in a daisy chain. Each slave reads its data on the fly and writes its response into the same frame as the frame continues downstream. The master receives the returning frame and updates the process image in a single bus cycle.

Three architectural constraints follow from this design:

1. Master requirement. A slave cannot initiate communication. If no master is transmitting the EtherCAT datagram, every slave on the segment remains in the EtherCAT State Machine Init state and presents zero process data.
2. Slave-only SERVOPACK. The Yaskawa SGD7S-R90F0A0A is a slave. The trailing F0 designator in the Yaskawa catalog code indicates EtherCAT communication. Other Sigma-7 variants use A0 (analog/pulse), E0 (MECHATROLINK-III), and M0 (Modbus/TCP). Each variant is a different hardware build with a different network interface ASIC and firmware, and the F0 variant has no IP stack at all.
3. No native master in desktop LabVIEW. LabVIEW on a Windows PC includes NI-VISA, NI-DAQmx, and various Ethernet/IP and Modbus I/O servers, but it does not include an EtherCAT master stack. You must add a third-party or NI EtherCAT master to the host (TwinCAT 3, SOEM, acontis) or move the master into a real-time target (NI CompactRIO with NI-IC for EtherCAT, NI PXI with NI-IC for EtherCAT, Beckhoff CX controller).

2. Confirming the Diagnosis

Before buying hardware, validate the failure mode with these checks.

The Wireshark check is the most decisive. If EtherType 0x88A4 traffic is absent, the segment has no master. If traffic is present but no slave is detected, the issue is downstream (ESI, topology, node address, or wiring).

3. Solution Matrix

Four engineering paths resolve the issue, ranked by field deployment likelihood.

4. Path A — NI CompactRIO 9056 as EtherCAT Master

The CompactRIO 9056 is a supported EtherCAT master target. Follow this commissioning sequence.

4.1 Prerequisites

• LabVIEW 2018 SP1 or later (2021 recommended for the 9056 Linux RT image).
• LabVIEW Real-Time Module licensed for the cRIO target.
• NI-Industrial Communications for EtherCAT driver installed on the host PC. The driver package is NI part number 781002-01 (English). Confirm driver/target compatibility on the NI-IC for EtherCAT documentation hub.
• NI Linux Real-Time image installed on the cRIO-9056 (the default factory-shipped image).
• Yaskawa ESI file for the SGD7S. Yaskawa publishes the Yaskawa_SGD7S_EtherCAT.xml ESI on the Sigma-7 download portal at yaskawa.com/products/motion/sigma-7. Copy it into the EtherCAT master ESI directory on the host before opening the LabVIEW project.

4.2 Wiring Topology

EtherCAT requires a daisy chain. Do not use an Ethernet switch between master and slave. The cRIO-9056 has dedicated EtherCAT ports on the controller; on most cRIO-905x models the left Ethernet port is reserved for EtherCAT when the EtherCAT master is enabled in the project. Consult the controller's CompactRIO model documentation for the exact port assignment on the 9056 variant you have.

1. Patch from the cRIO EtherCAT port (typically port 0) to the SGD7S port CN6A (EtherCAT IN).
2. If you have a second slave, patch CN6B (EtherCAT OUT) of the first slave to CN6A of the next slave.
3. If the SGD7S is the last (or only) slave, leave CN6B unconnected. EtherCAT slaves auto-terminate internally.

4.3 Project Configuration

1. In LabVIEW, create a new project and add the cRIO-9056 target as a Real-Time target.
2. Right-click the target and select New > EtherCAT Master. The master item appears under the target.
3. Right-click the EtherCAT Master item and select Scan for Slaves. The SGD7S should appear with its configured Node ID (station alias).
4. If the SGD7S does not appear, verify the ESI file is in the correct directory: C:\\Program Files (x86)\\National Instruments\\Shared\\EtherCAT\\ESI\\ on the host. Restart the master scan after copying.
5. Drag the SGD7S from the scan results into the project under the master. The default PDO mapping is loaded.
6. Set the master's cycle time. A 1 ms cycle time is a robust default for Sigma-7. 250 µs is achievable for high-dynamics axes, but the cRIO-9056 CPU budget must accommodate the full scan.

4.4 Default PDO Mapping on the SGD7S

Yaskawa's default ESI configures the following PDO groups. The PDO contents follow the CiA 402 (IEC 61800-7-201) drive profile.

You can remap PDOs in the master's PDO editor. Adding objects such as 0x6077 (Torque Actual Value, I16) and 0x60F4 (Following Error Actual Value, I32) is common for monitoring and protection.

5. Path B — NI PXI as EtherCAT Master

The same NI-Industrial Communications for EtherCAT driver supports PXI controllers. The PXI platform is preferred for high-channel deterministic test stands where a CompactRIO CPU budget is exceeded. The commissioning steps mirror Path A, with the differences below.

• Install the NI-IC for EtherCAT driver on the PXI controller and confirm the controller is on the supported list.
• Use the controller's dedicated EtherCAT port (PXIe controllers since 2017 typically have one). On older controllers, add a PXI Ethernet card such as the NI PXIe-8238 and designate it as the EtherCAT port in NI Measurement & Automation Explorer (MAX).
• The PXI controller's CPU budget is much larger than the cRIO-9056; you can typically run 8–32 Sigma-7 axes on a PXIe-8861 with a 250 µs cycle time.

6. Path C — Third-Party EtherCAT Masters

When no NI RT hardware is available, several options run on a Windows PC.

6.1 Beckhoff TwinCAT 3

TwinCAT 3 runs as a real-time extension on a Windows PC and provides a complete EtherCAT master. The free-of-charge TC3 PLC HMI Engineering download from beckhoff.com/twincat includes the EtherCAT master and the TwinCAT NC PTP motion controller, valid for development use. Production runtime requires a TC3 license.

From LabVIEW, drive TwinCAT via the TwinCAT ADS protocol over TCP. Use the Beckhoff TcAdsDll.dll or the open-source pyads library if your LabVIEW code is allowed to shell out to a helper process. Typical ADS settings: NetId 127.0.0.1.1.1 for local, Port 851 for the PLC instance, and one read/write per axis per cycle.

6.2 SOEM — Simple Open EtherCAT Master

SOEM is an open-source C library hosted at github.com/OpenEtherCATsociety/SOEM. Bind it to a real-time capable Intel NIC port on the host. SOEM is suitable for lab tests and embedded masters; the library can be wrapped as a DLL and called from LabVIEW through a Call Library Node.

6.3 acontis EC-Master and Koenig-Pa Port

acontis technologies and Koenig-Pa (Port) sell commercial EtherCAT master stacks for Windows and embedded targets with formal ETG conformance certification. They are the standard choice for OEM equipment that must pass EtherCAT PICS compliance testing.

7. Path D — Replace the SERVOPACK Variant

If the application can accept a non-EtherCAT network, ordering a different Sigma-7 variant avoids the entire EtherCAT master problem. Yaskawa's Sigma-7 catalog exposes several communication options on the same motor platform.

For a single-axis application where LabVIEW sends a position setpoint every 10–100 ms and reads back actual position, the Modbus/TCP variant is the lowest-friction option and requires no extra hardware beyond the drive and a Cat5e cable.

8. SGD7S EtherCAT Object Dictionary Highlights

Sigma-7 EtherCAT drives expose a CoE (CANopen-over-EtherCAT) object dictionary aligned with CiA 402. The subset below is what you will read or write most often when commissioning.

Yaskawa-specific objects live in the 0x2000–0x2FFF range and provide SDO access to drive parameters that mirror the front-panel Pn-parameters. Reading 0x2000 + Pn-number returns the current value; writing stores to non-volatile memory after a 0x1010 store cycle.

9. EtherCAT State Machine and Commissioning Sequence

Once a master is on the wire, the SGD7S progresses through the EtherCAT State Machine (ESM) before any process data is exchanged.

To transition from Op to a motion-enabled state, the CiA 402 controlword sequence is required.

Once the drive is in Operation Enabled, write to 0x607A (Target Position) in Profile Position mode, or stream setpoints in Cyclic Synchronous Position mode (object 0x6060 = 8). The statusword bit 10 (Target Reached) signals the move complete in PP mode; in CSP mode the move is continuous and bit 10 is reserved.

10. Verification Procedure

1. Power the SGD7S from a 200 V or 400 V three-phase bus (the R90 90 W class accepts single-phase 200 V input in most regions — confirm against the drive nameplate before applying power).
2. Patch the cRIO EtherCAT port to CN6A on the drive.
3. Run the LabVIEW project. Right-click the EtherCAT Master and confirm the slave reads Op in the runtime monitor.
4. Open the drive's front panel and confirm the display shows A.021.
5. From the LabVIEW front panel, write a non-zero Target Position (0x607A) in Profile Position mode, set the start bit (0x6040 bit 4), and confirm the motor moves one revolution (or whatever test distance was configured).
6. Read back 0x6064 Position Actual Value and confirm the value tracks the target within the configured following-error window.
7. Command a controlled stop by writing 0x6040 = 0x0007 (disable operation, motor remains energised), then 0x0006 (shutdown), then 0x0000 (disable voltage, motor de-energised).

11. Troubleshooting Matrix

12. Safety, EMC, and Error Code Reference

The Sigma-7 SERVOPACK includes two hardware-base-block inputs (HWBB1 and HWBB2) that remove drive output to the motor independent of software. Wire both inputs to safety-rated contacts for any application where unintended motion could cause harm. The drive will refuse to enter Operation Enabled state with either HWBB input open and will display A.Eb1 (HWBB1 open) or A.Eb2 (HWBB2 open).

EtherCAT cable shielding must be bonded to the drive's D-sub shell at both ends with 360° clamp-on ferrules, not pigtails. The CN6A and CN6B connectors on the SGD7S are metal-shelled D-codes; do not use plastic-shelled RJ45 plugs in industrial installations.

Common Sigma-7 front-panel alarm codes that affect EtherCAT commissioning: