OMRON CPM1A Series Modules: CPM1A-MAD01

Technical Dossier

Product Details And Specifications

OMRON CPM1A Series: Comprehensive Module Range and Technical Overview

The OMRON CPM1A series is a compact, fixed-configuration programmable logic controller platform that achieved widespread deployment across global heavy industry from the mid-1990s through the 2010s. Installations span petrochemical refineries, chemical processing plants, water treatment facilities, pharmaceutical manufacturing lines, and auxiliary control loops in nuclear power station balance-of-plant systems. The CPM1A architecture is characterized by its integrated CPU-and-I/O base unit design, supplemented by a defined range of expansion I/O and special-function modules. Its compact DIN-rail form factor, 24 VDC power supply compatibility, and ladder-logic programming via OMRON's CX-Programmer software made it a default selection for machine-level and process-cell automation where a full-scale DCS was not justified.

The Evolution of CPM1A Architecture

The CPM1A succeeded the CPM1 series, retaining instruction-set compatibility while expanding the maximum I/O point count and introducing analog expansion capability. The base CPU units were offered in 10-, 20-, 30-, and 40-I/O configurations, each available in AC-input/relay-output, DC-input/relay-output, and DC-input/transistor-output (NPN/PNP) variants. Expansion units attach via a proprietary side-bus connector, with a maximum of three expansion units per CPU. Special-function modules — including the CPM1A-MAD01 analog I/O unit — connect to this same expansion bus and consume one expansion slot.

The CPM1A was eventually superseded by the CP1E, CP1L, and CP1H series, which offer USB programming ports, higher instruction throughput, and expanded memory. However, the CPM1A remains in active service at thousands of installed sites where replacement of the entire control panel is not economically justified. OMRON officially classified the CPM1A as a mature/end-of-life product line; replacement parts and CPU units are no longer manufactured in volume, making secondary-market sourcing the primary procurement channel for maintenance operations.

CPM1A Full Catalog & Functionalities (SKU List)

CPU Units

• CPM1A-10CDR-A: 10-I/O CPU, AC power, relay output, 6 DI / 4 DO
• CPM1A-20CDR-A: 20-I/O CPU, AC power, relay output, 12 DI / 8 DO
• CPM1A-30CDR-A: 30-I/O CPU, AC power, relay output, 18 DI / 12 DO
• CPM1A-40CDR-A: 40-I/O CPU, AC power, relay output, 24 DI / 16 DO
• CPM1A-20CDT-D: 20-I/O CPU, DC power, NPN transistor output, 12 DI / 8 DO
• CPM1A-40CDT-D: 40-I/O CPU, DC power, NPN transistor output, 24 DI / 16 DO
• CPM1A-40CDT1-D: 40-I/O CPU, DC power, PNP transistor output, 24 DI / 16 DO

Digital Expansion I/O Units

• CPM1A-8ED: 8-point digital input expansion unit, 24 VDC
• CPM1A-8ER: 8-point relay output expansion unit, 250 VAC / 2 A
• CPM1A-8ET: 8-point NPN transistor output expansion unit, 24 VDC
• CPM1A-16ED: 16-point digital input expansion unit, 24 VDC
• CPM1A-16ER: 16-point relay output expansion unit, 250 VAC / 2 A
• CPM1A-20EDR: 20-point mixed I/O expansion, 12 DI / 8 relay DO

Analog Special-Function Units

• CPM1A-MAD01: 2-ch analog input (0–10 V / 4–20 mA), 1-ch analog output (0–10 V / 4–20 mA), 256-step resolution
• CPM1A-MAD11: 2-ch analog input (0–10 V / 4–20 mA / 0–5 V), 1-ch analog output, 4000-step resolution

Communication & Peripheral Units

• CPM1A-CIF01: RS-232C adapter for host-link / no-protocol serial communication
• CPM1A-CIF11: RS-422A/485 adapter for multi-drop host-link networks

Sourcing Hard-to-Find & Obsolete CPM1A Parts

With OMRON having discontinued volume production of the CPM1A line, procurement of replacement modules — particularly CPU units and the CPM1A-MAD01 analog expansion — relies on specialist distributors maintaining tested surplus inventory. DriveKNMS maintains a dedicated stock pool of CPM1A-series modules sourced from decommissioned panels, factory overstock, and authorized secondary-market channels. Each unit undergoes functional verification before dispatch. For sites operating under long-term maintenance contracts where panel replacement is deferred, DriveKNMS provides lifecycle extension support including cross-reference advisory (e.g., migration path to CP1E or CP1L where direct replacement is unavailable) and consignment stocking arrangements for high-volume maintenance customers.

Quality Control for the CPM1A Range

CPM1A modules present specific test requirements due to their integrated bus connector design and the analog signal conditioning circuitry in units such as the CPM1A-MAD01. DriveKNMS applies the following verification protocol to all CPM1A stock:

• Visual inspection of the side-bus expansion connector pins for deformation, oxidation, or mechanical damage.
• Power-on functional test: CPU units are loaded with a diagnostic ladder program and cycled through all I/O points under controlled load.
• For analog units (CPM1A-MAD01, CPM1A-MAD11): input channel linearity is verified across the full 0–10 V and 4–20 mA ranges using a calibrated signal source; output channel accuracy is measured against a precision multimeter.
• Communication adapter units (CPM1A-CIF01, CPM1A-CIF11) are tested for RS-232C and RS-422/485 signal integrity at 9600 and 19200 baud.
• All units are powered for a minimum 2-hour burn-in period prior to packaging.