Bachmann CNT204 Counter Module

Technical Dossier

Product Details And Specifications

Bachmann M200 Series Technical Notes

The Evolution of M200 Series Architecture

The Bachmann M200 platform was introduced as a successor to earlier single-board controller architectures, consolidating CPU, I/O, and communication functions into a standardized backplane bus system. Early revisions used a proprietary parallel backplane with fixed slot addressing; later hardware generations introduced a high-speed serial backplane (SBus) that increased inter-module bandwidth and reduced cycle time jitter. The CNT204 counter module has been produced across multiple hardware revisions, with firmware updates addressing encoder interface compatibility (TTL, HTL, RS422 differential) and extended counting range (32-bit to 48-bit accumulator). Compatibility between M200 CPU generations (MPC240, MPC265) and I/O modules requires firmware version alignment — a critical consideration for spare part procurement in mixed-revision installations. The platform entered its mature/maintenance phase; Bachmann has shifted primary development resources to the M1 series, making long-term spare part availability for M200 modules a strategic concern for plant operators.

M200 Series Full Catalog & Functionalities (SKU List)

Counter & Encoder Modules

• CNT204: 4-channel high-speed counter module; TTL/HTL/RS422 encoder input; 32-bit accumulator; frequency measurement up to 1 MHz.
• CNT202: 2-channel counter/encoder interface; supports SSI absolute encoders; 24-bit resolution.

Digital I/O Modules

• DIO232: 32-channel digital input module; 24 VDC; IEC 61131-2 Type 1/3 compatible.
• DIO248: 48-channel mixed digital I/O; configurable input/output ratio per channel group.
• DIO280: 80-channel high-density digital I/O; backplane bus optimized for large-scale discrete control.
• DIO216: 16-channel digital output module; 24 VDC sourcing; 0.5 A per channel; short-circuit protected.

Analog I/O Modules

• AIO288: 8-channel analog input / 8-channel analog output; ±10 V / 0–20 mA; 16-bit resolution.
• AIO120: 20-channel analog input; 4–20 mA / 0–10 V; 12-bit resolution; field-wiring terminal block.
• AIC212: 12-channel analog current input; 4–20 mA; HART pass-through capable on select firmware.
• AIC208: 8-channel analog current output; 4–20 mA; 16-bit DAC; loop-powered field devices.

Temperature & Specialty Measurement

• TMP200: 8-channel thermocouple input module; supports J, K, T, E, N, R, S, B types; cold-junction compensation onboard.
• TMP204: 4-channel RTD input module; PT100/PT1000; 3-wire and 4-wire connection; 0.1 °C resolution.

Communication & Gateway Modules

• GMP232: PROFIBUS-DP slave interface module; up to 12 Mbit/s; supports GSD file configuration.
• GMP212: PROFIBUS-DP master module; manages up to 125 slave nodes; diagnostic buffer onboard.
• RS204: 4-port serial communication module; RS232/RS485 configurable per port; Modbus RTU master/slave.
• EXC208: 8-slot I/O expansion chassis interface; extends backplane to remote rack; fiber-optic isolation option.
• ISI222: Industrial serial interface module; supports DNP3 and IEC 60870-5-101 protocols.
• NT255: Network time synchronization module; GPS/IRIG-B input; distributes time reference across M200 backplane.

CPU & Controller Modules

• MPC240: Main CPU module; 400 MHz processor; 64 MB RAM; dual Ethernet; IEC 61131-3 runtime; supports SIL 2 applications with certified firmware.
• MPC265: Enhanced CPU module; 800 MHz processor; 128 MB RAM; USB configuration port; extended diagnostic logging.