Eaton COM-MPB1-TP/COM-MPB2-TP communication module

Eaton COM-MPB1-TP/COM-MPB2-TP communication module

Physical product

Display two board modules:

MPB1-TP: The panel has an ERROR error indicator light, ACTIV activity indicator light, and COM-PORT (DB9 serial port);

MPB2-TP: In addition to ERROR, ACTIV indicator lights, and COM-PORT, the panel is additionally equipped with MPI DB9 interface. Both models are card based communication expansion modules.

Security Warning

Warning: It is prohibited to carry out operations without reading the operation manual

If a complete operation manual is missing and only scattered pages are used, equipment damage and personal injury may occur due to neglecting safety information.

Before using the device, it is necessary to prepare a complete set of documents and read the "Safety Requirements" chapter.

All assignments must strictly follow the complete original document and cannot only use partial pages.

Factory default configuration (hardware interface+firmware)

All hardware interface types of the products are RS485, and the factory settings for bus terminal resistance and firmware are shown in the following table:

Configuration item MPB1 TP MPB1 TP MODB32 MPB2 TP

Interface type RS485 RS485 RS485

Bus terminal resistance OFF ON OFF

Firmware mode ALT (PS40) ALT (MODB32 Modbus32) ALT (MPI)

Explanation:

MPB1-TP MODB32 is a Modbus specific variant version of MPB1-TP, with bus terminal resistors enabled at the factory;

The MPB2-TP factory firmware is in MPI protocol mode.

Practical troubleshooting and replacement of typical communication faults

In complex on-site environments, when facing communication issues caused by COM-MPB1-TP or COM-MPB2-TP, it is recommended to follow the following process for troubleshooting:

1. Intermittent disconnection after hardware replacement

Phenomenon: The communication module was replaced with a new one and initially operated normally. However, as the equipment ran for a longer period of time or the motor started and stopped frequently, communication experienced intermittent interruptions.

Troubleshooting: First, check the factory model label of the new module. If MPB1-TP MODB32 (with built-in ON resistor) is used but connected in the middle of the bus, the local terminal resistor should be disconnected (or the module should be moved to the end). Secondly, check if the shielding layer of the communication cable is grounded at one end according to the specifications (usually on the main station side), as electromagnetic interference generated by frequent motor start stop will couple to the unshielded RS485 line.

2. The message is sent normally, but there is no response received

Phenomenon: The upper computer software displays that the transmit message (TX) indicator light is flashing normally, but the receive (RX) has no data, indicating a timeout.

Troubleshooting: Confirm the compatibility of firmware protocols between both parties. If it is MPB2-TP (MPI firmware), connecting to a regular Modbus master will inevitably fail. At this point, it is necessary to confirm with the original factory or supplier whether there is a matching Modbus firmware that can be flashed, or if it must be replaced with COM-MPB1-TP MODB32 version. At the same time, use a multimeter to measure the voltage of RS485's A line to ground and B line to ground, and confirm whether there is a short circuit to ground or reversed wiring (A to B, B to A).

3. Signal attenuation caused by too many bus nodes

Phenomenon: After adding new device nodes, the existing communication network begins to frequently report errors.

Troubleshooting: The RS485 standard stipulates that a single segment bus can mount up to 32 nodes (Unit Load). If the receiver impedance of the module is not the standard 1/8 or 1/4 unit load, as the number of nodes increases, the bus capacitance increases and the signal edge becomes slower. At this point, if you do not replace the high impedance module that supports more nodes, you can try reducing the communication baud rate and checking if all terminal resistors of the COM-MPB1-TP module are correctly configured (only both ends are ON).