For a Balluff BNI00K6 connected through a BNI00CM, configure the EtherCAT device description and I/O path in TwinCAT first; use the device’s CoE tab for an identified parameter, not arbitrary output bytes. The exact parameter or object is not named here, so locate it in the applicable Balluff device documentation before writing a value.
Which path carries configuration and which carries valve commands?
TwinCAT sends EtherCAT configuration through the master to the scanned and configured devices. The ESI device description supplies TwinCAT with the device’s identity and configuration information so the master can represent it in the I/O tree. After configuration, cyclic process data travels through the EtherCAT I/O mapping; the reported physical path continues from the BNI00K6 to the BNI00CM and then to the valves.
CoE access is a separate route for device parameters. Select the relevant device in TwinCAT and open its CoE tab to inspect or access the available objects. A missing output pin in the I/O view and a parameter that must be changed online are different problems: the former concerns process-data mapping, while the latter concerns an object exposed for CoE access. Do not substitute one route for the other.
Trace the path in order: physical device and EtherCAT connection, master configuration, device I/O mapping, then the BNI00CM port and valve. A failure at an earlier hop can make later settings appear ineffective.
Which TwinCAT approach fits each task?
| Approach | Use it for | What it tells you |
|---|---|---|
| Install the ESI and reload device descriptions | Making a device description available to TwinCAT | The device can then be selected and represented in the I/O configuration. |
| Scan the EtherCAT master and add the discovered boxes | Building the configured topology from connected hardware | The scanned device layout, including boxes shown under the master. |
| Inspect the device’s CoE tab online | Finding or changing a parameter exposed through CoE | Objects and values presented by the selected device. |
| Use mapped cyclic I/O | Sending runtime output data to the BNI00CM and valves | Whether the output pin or process-data fields are available to the PLC. |
For initial setup, use the ESI plus a hardware scan, then add the scanned boxes and inspect the topology. Use CoE only after identifying the intended parameter. Use cyclic output data only after confirming the mapping and meaning of each byte or bit.
Why can the revision color or missing slots be misleading?
The observed TwinCAT comparison uses green when the revision matches and blue when it differs; a blue indication can still represent a usable device. Select the difference checkbox in the comparison dialog to inspect what differs instead of treating color alone as a failure. Confirm the actual device revision and the detected/configured difference before accepting the configuration.
A device shown under the EtherCAT master may not present “slots” in the way expected from another PLC platform. The reported setup was resolved by deleting the existing EtherCAT master items, scanning the connected hardware, and adding the discovered boxes. In TwinCAT, inspect the master’s EtherCAT tab and Topology view to see how the devices are arranged. Do not assume the absence of slot terminology means no hardware was found.
How do you make BNI00K6 available to the master?
- Obtain the ESI device description from the official Balluff BNI00K6 product page. Confirm that the description corresponds to the hardware being configured.
- Install the ESI in TwinCAT using Beckhoff’s instructions for updating the ESI device description.
- Reload the device descriptions so the newly installed device definition is available in the EtherCAT configuration.
- With the hardware connected, scan the EtherCAT master. Review the detected devices and add the discovered boxes to the configuration rather than relying on a guessed slot layout.
- Open the master’s EtherCAT tab and Topology view. Compare the displayed path and device order with the physical connection, including the BNI00K6-to-BNI00CM segment.
If TwinCAT reports a revision difference, inspect the difference details before deciding whether the configured device matches the connected unit. A successful scan establishes that devices were discovered; it does not by itself prove the valve output mapping or parameter values are correct.
How do you locate and change the intended CoE parameter?
Select the device that owns the parameter, then open its CoE tab and inspect the available objects. First establish whether the requested setting belongs to the BNI00K6, the BNI00CM, or a valve. The hardware chain contains multiple devices, and changing an object on the wrong node will not configure the intended function.
- Identify the parameter by name and purpose in the applicable device documentation. Record its object index, subindex if applicable, data type, allowed range, and whether it is readable or writable.
- In TwinCAT, select that device and open the CoE tab. Locate the documented object and compare the displayed current value with the intended setting.
- Write only a value that matches the documented type and range, using the online CoE controls for that object. If the object is absent or read-only, check that the correct device is selected and that its device description and online state are appropriate; do not substitute a similarly named object.
- Read the object again after the write. If the value does not persist as needed after a restart or power cycle, check the device documentation for its storage behavior and required save procedure rather than assuming an online write is permanent.
The available report mentions an “Output Pin 2 Object” but does not identify its exact object address or explain what setting it controls. Treat that label as a clue to inspect the corresponding device documentation and CoE list, not as sufficient identification for a write.
Why do the BNI00CM ports change color when you send FF FF?
The reported behavior is specific: sending FF FF to the output data turns all BNI00CM ports red; without those bytes, the ports appear yellow, and the system still does not work. Those colors alone do not identify whether the cause is an invalid output value, an I/O mapping mismatch, a device/port condition, or a valve-side issue. Do not treat all-ones data as a neutral test pattern; its meaning depends on the mapped fields and device behavior.
| Observed state | What to check next |
|---|---|
Ports turn red when FF FF is sent |
Inspect the online port/device diagnostics and determine what each output bit or byte controls. Compare the sent data with the documented output mapping and permitted values. |
Ports appear yellow without FF FF, but valves do not operate |
Check whether the PLC output is mapped to the intended process-data field, whether the master and device are online, and whether the BNI00CM port configuration matches the connected valve. |
| No output pin is visible | Inspect the configured device’s process-data/I/O view and confirm the correct device description and scanned box were added. Use CoE only for a documented parameter, not as a replacement for a missing cyclic output mapping. |
Read the exact diagnostic text or status for the red/yellow indication in TwinCAT and on the device, then trace the output from PLC mapping to BNI00K6, BNI00CM, port, and valve. The color is a symptom to investigate, not enough information to assign a fault cause.
How do you verify the complete device and output path?
- Confirm TwinCAT recognizes the connected EtherCAT devices after the ESI reload and scan. Resolve any revision difference by inspecting its details.
- Compare the configured master topology with the physical chain, including the BNI00K6 and BNI00CM.
- Confirm the intended output pin or process-data field exists in the I/O configuration and is mapped to the PLC variable that writes it.
- Use a documented, valid output value and monitor the mapped value online. Avoid unverified
FF FFtest data. - Read the selected CoE parameter back after any change, and inspect the individual device/port diagnostics while checking whether the valve responds.
If communication and topology are correct but the output still fails, compare the configured process-data layout, the BNI00CM port setup, the connected valve requirements, and the relevant diagnostic status. Change one identified setting at a time so the next observation isolates a specific hop.
Frequently asked questions
Why does TwinCAT show no slots for the EtherCAT device?
Use an EtherCAT scan and add the discovered boxes, then inspect the master’s EtherCAT Topology view. TwinCAT’s box-based layout does not necessarily use the slot concept expected from another PLC platform.
Why is the BNI00K6 revision shown in blue?
The described comparison uses blue for a different revision, which can still work. Select the difference checkbox and inspect the specific differences before deciding whether the connected and configured devices match.
Why do BNI00CM ports turn red with FF FF output data?
The reported ports turn red when FF FF is sent, but the color does not identify the cause by itself. Check the output mapping, documented meaning and valid values of each field, and the device’s online diagnostics.
How do I change a parameter in TwinCAT CoE online?
Select the device that owns the setting, open its CoE tab, locate the documented object, and write a value within its specified type and range. Read it back and check the device documentation for persistence behavior.