Schneider Electric ASMBKT185 Modbus Plus Terminator Connector

Configured for high-frequency signal impedance matching within Modbus Plus communication networks, the Schneider Electric ASMBKT185 (AS-MBKT-185 Line Terminator) provides direct physical/electrical execution. This passive hardware accessory installs directly into network junction boxes to eliminate electrical wave reflections along the differential twisted-pair data lines. By terminating both extreme ends of the physical trunk segment with a precise resistive load, this component prevents signal attenuation and data packet corruption across Modicon automation platforms.

Hardware Specifications

Backplane Bus Communication Velocity and Signal Impedance Matching

This line terminator operates at the physical layer of the network, maintaining the structural baseline required for deterministic backplane bus communication velocity and node synchronization. When multi-drop architectures link various Modicon controllers, signal reflections naturally occur at the cable boundaries where the cable ends. The internal resistor network of the ASMBKT185 matches the characteristic impedance of the 1 Mbps token-passing cable, dissipating residual energy frames that would otherwise rebound and interfere with active data packets. This physical stabilization allows the industrial network to maintain low error rates and predictable token rotation times across long distances.

Frequently Asked Questions

Q: Where exactly must the two line terminators be placed inside a Modbus Plus network topology? A: The two terminators must be installed exclusively at the two physical ends of the main trunk cable segment. Installing terminators at intermediate drop nodes or junction boxes will over-load the network transceiver circuitry, dropping the differential signal voltage below operational thresholds.

Q: Can this passive connector be deployed on standard RS485 or Modicon Remote I/O (RIO) coaxial networks? A: No. The ASMBKT185 is engineered with specific internal resistance values mapped strictly to the characteristic impedance of standard Modbus Plus twisted-pair shielded cables. Deploying this hardware on RIO coaxial paths or standard RS485 loops will cause an impedance mismatch, disrupting network data frames.

Q: Given that this component was discontinued on 27 March 2026, what is the recommended long-term system solution? A: Because there is no direct replacement for this legacy network accessory, long-term system planning should involve migrating obsolete communication lines to Ethernet-based architectures, such as Modicon M580 PAC platforms running Modbus TCP or EtherNet/IP.

Field Installation Guidelines

• Junction Box Seating: Insert the terminator pin assembly firmly into the designated port of the 990NAD23000 junction box, verifying that the mechanical latch engages completely.
• Shield Wire Continuity: Ensure that the cable shield wire bypasses the terminator block smoothly and terminates to the local panel ground rail at only one designated point to prevent ground loops.
• Conduit Bending Radii: Maintain standard industrial bending clearances for the incoming network cables entering the junction box to prevent internal physical strain on the terminator pins.
• Environmental Sealing: Install the completed junction box and terminator assembly inside an enclosure rated IP54 or higher when deploying in environments prone to conductive dust or moisture.