OMRON CQM1-DA021 Analog Output Module with IPS02 Power Supply

The OMRON CQM1-DA021 is a 2-channel analog output module designed for the CQM1 series programmable logic controllers. This module converts digital values from the PLC CPU into analog voltage or current signals for controlling devices such as variable speed drives, valve positioners, and analog meters. The CQM1-IPS02 is a power supply unit that provides the necessary DC power to the CQM1 system. These modules are part of the compact CQM1 PLC family, widely used in small to medium-scale industrial automation. The CQM1-DA022 is a compatible alternative with similar functionality.

Product Overview

The CQM1 series from OMRON is a compact modular PLC system that combines high performance with small physical size, making it suitable for machine control, assembly stations, and small process applications. The CQM1-DA021 analog output module expands the PLC's capability to generate analog signals, enabling precise control of analog actuators. The module provides two independent output channels, each configurable for voltage or current output. The CQM1-IPS02 power supply unit is used to power the CQM1 CPU and I/O modules when an external 24V DC source is available or when higher current capacity is needed than the CPU's built-in supply. The CQM1-DA022 is an alternative model that may offer different output ranges or resolution; it is compatible with the same CQM1 system and can be used interchangeably in many applications. All modules mount on the CQM1 backplane and are connected via the internal bus.

CQM1-DA021 Technical Specifications

The CQM1-DA021 provides two analog output channels. Each channel can be independently configured for voltage output (0 to 10 VDC, -10 to +10 VDC) or current output (4 to 20 mA). The resolution is 12 bits (4096 steps) for voltage output and 11 bits (2048 steps) for current output. The conversion speed is 2 milliseconds per channel (2 ms for both channels when updated together). The output accuracy is ±0.5% of full scale at 25°C, with a temperature coefficient of ±0.05% per °C. The output load resistance for voltage output is minimum 2 kΩ; for current output, maximum load resistance is 600 Ω. The module includes output hold functionality: when the PLC is in program mode or if a communication error occurs, the outputs can be set to hold last value, go to a preset value, or go to zero. The module requires 5V DC from the backplane (0.2 A) and also uses the 24V DC external supply for the analog circuits. The module occupies one slot in the CQM1 rack. The external connection is via a removable terminal block with screw terminals.

CQM1-DA022 Compatibility

The CQM1-DA022 is another analog output module for the CQM1 series, often considered a replacement or alternative to the DA021. The DA022 typically provides 2 channels with similar voltage ranges (0-10V, -10-+10V) and 4-20mA current output. The key difference may be in the resolution (still 12-bit) and the conversion speed. The DA022 is compatible with the same CQM1 CPU units (CQM1-CPU11, CQM1-CPU21, CQM1-CPU43, etc.) and can be used in the same rack as the DA021. The configuration of the DA022 is similar, using the same programming software (CX-Programmer or SYSMAC-CPT). The I/O allocation for the DA022 is typically 2 input words (for status) and 2 output words (for the analog values). The DA022 includes LED indicators for power and output status. When replacing a DA021 with a DA022, it is important to verify that the output ranges and wiring are compatible, as pin assignments may differ slightly. The DA022 may also offer improved accuracy or additional diagnostic features. Users should refer to the CQM1 analog I/O manual for specific differences.

CQM1-IPS02 Power Supply Specifications

The CQM1-IPS02 is a power supply unit designed for the CQM1 system. It provides 24V DC power to the CPU and I/O modules. The input voltage is 100-240V AC (50/60 Hz) or 24V DC (depending on the variant; the IPS02 is typically AC input). The output capacity is 2.8 A at 5V DC for logic and 0.4 A at 24V DC for I/O circuits (some versions may vary). The power supply unit mounts to the left of the CPU on the CQM1 backplane. The IPS02 includes overload and overvoltage protection. LED indicators show power on and output status. The unit's dimensions are approximately 70 mm wide, 100 mm high, and 85 mm deep. The operating temperature range is 0°C to 55°C. The power supply unit must be properly grounded to ensure safe operation and noise immunity. The IPS02 is compatible with all CQM1 CPU units and I/O modules. When calculating the total power budget, the current consumption of all modules in the system must not exceed the supply's capacity. Typical current consumption: CPU (~0.5A at 5V), digital I/O modules (~0.1-0.2A each), analog modules (~0.2A at 5V plus 24V external).

Analog Output Configuration

Configuring the CQM1-DA021 or DA022 involves setting the output range for each channel via DIP switches or software (depending on the model). The output value is written from the PLC program to the assigned output words. For example, if the module is assigned unit number 0, the output word for channel 1 might be n+1 (where n is the base address). The digital value corresponds to the output signal linearly: for 0-10V range, a digital value of 0 gives 0V, and 4095 gives 10V. The user program must scale the desired engineering units (e.g., 0-100% flow) to the appropriate digital value. The module also provides status words that can be monitored to detect errors such as no external 24V power or output range mismatch. The module's output hold function can be set to maintain the last value or a preset safe value when the PLC is in program mode or when a communication error occurs. This is critical for applications where a sudden output drop could cause damage (e.g., closing a valve suddenly).

Wiring and Connections

The CQM1-DA021/DA022 uses a removable terminal block for analog output connections. Typical pin assignments: For voltage output, terminals are marked V+ and COM for each channel. For current output, terminals are I+ and COM. The shield of the output cable should be connected to the COM terminal or to a dedicated ground terminal if available. The external 24V DC power supply (for the analog circuits) must be connected to the module's power terminals; this supply must be separate from the PLC's logic power supply or well-filtered. The maximum load resistance for current output is 600 ohms; exceeding this will cause the output to saturate. For voltage output, the load must be at least 2 kΩ. The output cables should be twisted-pair shielded and routed away from high-power AC wires. The shield should be grounded at one end only (usually at the PLC side) to avoid ground loops. The terminal block accepts wire sizes 0.2 to 2.5 mm².

Programming Example

In a CQM1 PLC, the analog output value is written using the MOV (move) instruction. For example, assume the DA021 is unit number 0, and its output word is assigned to CIO word n+1. To set output channel 1 to 5V on a 0-10V range, the digital value is (5/10)*4095 = 2047 (approx). The program would load the constant #2047 into a data register and then MOV it to n+1. Scaling can be done using the SCL (scale) instruction or by manual calculation. For current output 4-20 mA, 0% = 4 mA corresponds to digital 0, and 100% = 20 mA corresponds to digital 4095 (or 2048 depending on resolution). The relationship is linear. The program can also read the module's status word to check for errors. It is good practice to include a timeout or watchdog that sets outputs to safe values if communication is lost.

Applications

The CQM1 analog output modules are used in applications where the PLC must control analog devices. Typical applications include speed control of small DC or VFD motors via a 0-10V speed reference; valve position control using 4-20 mA to position a pneumatic or electric actuator; pressure control where the analog output drives an I/P converter; temperature control using an analog output to a SCR power controller; and positioning control where the analog output commands a servo drive's torque or velocity mode. The compact size of the CQM1 makes it suitable for small machines, test stands, and laboratory automation. The analog modules are often combined with analog input modules (e.g., CQM1-AD041) for closed-loop control applications such as PID temperature or pressure regulation.

Troubleshooting and Maintenance

Common issues with analog output modules include no output signal, incorrect output range, and erratic output. First, verify that the external 24V DC power is present and within tolerance. Check the DIP switch settings for output range. Use a multimeter to measure the output at the terminals while writing a known digital value from the PLC. If the output is zero, check the PLC's I/O table to ensure the module is recognized. If the output is unstable, check for wiring errors, ground loops, or electrical noise. The CQM1's self-diagnostic LEDs will indicate a module error. The modules have no user-serviceable parts; if defective, replacement is required. Keep the module free of dust and ensure proper ventilation. The terminal block screws should be re-tightened periodically.

Ordering and Compatibility Information

The CQM1-DA021 and CQM1-DA022 are discontinued products but remain in service in many existing installations. Replacement modules are available through industrial surplus suppliers. The CQM1-IPS02 power supply is also discontinued but widely available. For new designs, OMRON recommends the CP1H or CJ2M series with analog output modules (e.g., CJ1W-DA041). The CQM1 series is compatible with programming software CX-Programmer (versions supporting CQM1) and the older SYSMAC-CPT. The modules require a CQM1 CPU with sufficient I/O capacity; the CQM1-CPU43-EV1 is a common choice. When mixing analog modules with digital I/O, the total current consumption must be within the power supply's rating. The modules are not compatible with the newer CP1E or CP1L series without adapters.

Safety Precautions

When working with analog output modules, observe standard electrical safety practices. Disconnect power before wiring or removing modules. The external 24V DC supply must be SELV (Safety Extra Low Voltage) and isolated from the AC mains. Do not exceed the maximum load ratings for current or voltage outputs. Ensure proper grounding to prevent electric shock and noise. The analog outputs are not isolated from the PLC logic; therefore, the analog signal common is referenced to the same ground as the PLC. If isolation is required, use external signal isolators. The module is not rated for hazardous locations unless specifically certified. Always consult the CQM1 User Manual for detailed installation and safety instructions.