The EEM-MB370-EIP provides live power and current values through an EDS-based connection to the 5069-L320ERS2 at v32.11, but the 1768-L45 controllers at v16 and v19 fault when a Generic Ethernet Module is configured with a zero output size. Trace the connection from the PLC to the monitor, then validate the assembly sizes, configuration data, and project definition separately.
Where does the EtherNet/IP data path stop?
The successful 5069-L320ERS2 connection is a useful baseline: it shows that the monitor can communicate over EtherNet/IP and that its live power and current values can reach PLC tags. The failure is specific to the connection setup used by the 1768-L45 projects, where the EDS-based module configuration is not available and a Generic Ethernet Module is required.
Follow the data path in order: PLC module definition, EtherNet/IP connection request, monitor assemblies, then PLC input tags. The reported 16#0127 fault is a connection-request error reporting an invalid output size. That fault occurs before the input tags can be treated as proof of correct cyclic data exchange. A tag that retains a plausible value is not enough; confirm whether the connection is established and whether the input data changes without restarting the monitor.
Keep the known-good and failing configurations distinct. The EDS-based configuration that works on the 5069 controller does not prove that the Generic Ethernet Module parameters for the 1768 controller are correct. Conversely, a fault in the Generic module setup does not by itself indicate an Ethernet cable, switch, or IP-path failure.
Check before proceeding: Record the controller model and revision, whether the project uses the EDS profile or Generic Ethernet Module, the displayed module fault, and whether the monitor values update continuously in the working configuration.
What do assembly instances 101, 102, and 110 describe?
Use the assembly instances supplied for the monitor as the connection endpoints, and keep the instance identifiers separate from the data sizes. The size is the amount of data associated with an assembly; the instance number identifies the assembly.
| Connection role | Assembly instance | Supplied size | Engineering use |
|---|---|---|---|
| Input | 101 |
440 |
Monitor data sent to the PLC |
| Output | 102 |
0 |
No output data specified in the supplied setup |
| Configuration | 110 |
400 |
Configuration data associated with the connection |
The size values were supplied for the device setup as bytes. A Generic Ethernet Module dialog may ask for a number of elements based on the selected communication format rather than a byte count. If its size field is in elements, convert the byte count using the element width: 440 bytes correspond to 440 SINT elements, 220 INT elements, or 110 DINT elements; 400 bytes correspond to 400 SINT, 200 INT, or 100 DINT elements. Use those conversions only when the dialog’s size field is element-based and the device’s supplied sizes are byte counts. Do not change the assembly instance numbers during conversion.
Check before proceeding: Compare the controller’s configured byte totals with the supplied 440-byte input and 400-byte configuration sizes, accounting for the selected data type. Confirm that the instance numbers remain 101, 102, and 110.
How can you create the module without inventing output data?
The generic connection attempt that uses a nonzero output size is rejected online with 16#0127, “Connection Request Error. Invalid Output Size.” Entering an arbitrary nonzero value just to satisfy the module-creation dialog does not solve that fault. The supplied device setup specifies an output size of zero, so do not treat a placeholder size as valid device data.
- In a test project for the 1768-L45, add a Generic Ethernet Module and enter the supplied assembly instances.
- Select the input-only communication format reported to create the module without an output-size entry:
Input Data - INT - Run/Program. - Set the input data length to match the 440-byte assembly using the dialog’s size units. If the field takes INT elements, that is 220 elements; if it takes bytes, enter 440.
- Set the configuration data length to match the 400-byte configuration assembly using the same unit check. If the field takes INT elements, that is 200 elements; if it takes bytes, enter 400.
- Download and inspect the module status before judging the input values.
The user reported that this input-only format allowed module creation, unlike formats that required an output size. The values then behaved like a one-shot: a measured 118 V appeared after cycling monitor power, but removing the terminal wire did not update the tag until another power cycle. This is not a satisfactory live-data result. Treat the input-only format as a way to test the zero-output connection shape, not as proof that the full configuration is correct.
Check before proceeding: Confirm whether the module comes online without a yellow triangle and without an invalid-output-size fault. Then observe whether the input tag changes while the monitor remains powered.
What should the Generic Module send in configuration assembly 110?
The supplied configuration size is 400 bytes, a separate path from the 440-byte input assembly. The configuration array is not self-describing merely because the Generic Ethernet Module can allocate its storage. Without the EDS profile, the software may expose an array of data without the named parameters and value meanings that the profile would provide.
That distinction matters because a configured size does not establish that the configuration contents are correct. One proposed cause for the one-shot behavior was that the monitor expects configuration data and that the PLC may be sending zero-filled data when no values are explicitly set. Treat this as a diagnostic hypothesis, not as a confirmed cause. Do not populate the 400 bytes with guessed values: obtain the assembly mapping and required configuration values from the device documentation or the manufacturer, then map them to the PLC data in the specified order and format.
Inspect the Generic Ethernet Module configuration fields and the controller’s live configuration data, if available. Check whether the connection is sending configuration data, whether the data are all zeros, and whether any required settings have been assigned. A module that connects successfully can still carry incorrect or incomplete configuration contents.
Check before proceeding: Verify the expected configuration assembly contents against the monitor’s documented mapping. If the mapping is unknown, resolve that before treating successful module creation as a fix.
How do you rule out a corrupted module definition in v16 or v19?
Some RSLogix 5000 releases before roughly v20 were reported to corrupt Generic Ethernet Module assembly sizes when users edited the module object, even while offline. Under that failure mode, the displayed values could differ from the sizes and formats retained by the project. This was reported as a possible explanation, not a confirmed cause for these particular controllers.
- Create a new, empty project for the controller revision being tested.
- Add only one Generic Ethernet Module; enter the intended instance numbers, communication format, and sizes once.
- Save, download, and test that project without editing the module sizes in place.
- For a different size or format test, create another fresh project rather than changing the existing module object and downloading again.
Test v16 and v19 independently. A clean project isolates the module definition from edits made during earlier trials and makes the downloaded parameters easier to audit. If the clean project still reports the same output-size fault, return to the selected communication format and the device’s required assembly configuration rather than repeatedly changing the same module object.
Check before proceeding: Confirm the fresh project’s module parameters before download and compare the online status and input behavior with the prior project.
How can you verify that the PLC receives live measurements?
Separate connection status from data validity. First verify that the module is online without a module fault. Then compare the raw input data with the monitor’s displayed measurement or a known electrical condition. The observed 118 V reading and the reported response to removing the terminal wire provide a useful test pattern, but repeat such checks only under safe, controlled operating conditions.
- With the monitor powered and a stable measurement present, record the monitor value and corresponding PLC input tag.
- Change the measured condition or remove the monitored input as appropriate for the installation, then observe whether the PLC data changes while the monitor stays powered.
- Compare raw assembly data as well as interpreted tags. If raw data changes but the engineering value does not, check the tag offset, data type, and scaling against the assembly map.
- If neither raw data nor the interpreted tag updates until a monitor power cycle, review the communication format and configuration assembly contents; a latched-looking tag is not proof of a live input connection.
The available controller options also affect the setup path. The EDS file worked with the 5069-L320ERS2 at v32.11, while the 1768-L45 controllers at v16 and v19 were being configured as Generic Ethernet Modules. Check the supported EDS and controller-revision compatibility before considering a firmware change; do not assume an upgrade is available or compatible for a particular installation.
End-to-end check: With the connection online and the monitor still powered, change the measured input and verify that the raw PLC input and the correctly mapped engineering tag update without cycling power.
What should you check about the EEM-MB370-EIP connection?
How do I set the EEM-MB370-EIP output size to zero?
Use the input-only Input Data - INT - Run/Program format reported to permit module creation without an output-size entry. Confirm online that the controller no longer reports 16#0127; do not substitute an arbitrary nonzero output size.
How do I convert the 440-byte input size to INT elements?
If the Generic Ethernet Module size field counts INT elements, 440 bytes equals 220 INT elements. Confirm whether the field expects bytes or elements before entering the value.
How do I configure the 400-byte configuration assembly?
Use assembly instance 110 and the correct size units; 400 bytes equals 200 INT elements if the field counts INTs. Get the expected configuration contents from the device mapping instead of assuming the array should contain zeros or guessed values.
How do I confirm that the PLC input is live?
Keep the monitor powered, change or remove the monitored input under controlled conditions, and verify that both raw assembly data and the mapped tag update without a power cycle.