OMRON CQM1‑ARM21 2‑Channel Analog Output Unit for CQM1 PLC
The OMRON CQM1‑ARM21 is a dedicated analog output module for the CQM1 series PLC, providing two independent output channels. Each channel can be individually configured for voltage (0‑10 V DC) or current (4‑20 mA). With 12‑bit resolution (0‑4095) and an isolated design, this module is used to control proportional valves, variable frequency drives, servo torque references, and analog recorders.
Analog Output Specifications
Voltage output range: 0‑10 V DC (load impedance ≥ 2 kΩ). Current output range: 4‑20 mA (load impedance ≤ 600 Ω). Resolution: 12 bits (2.44 mV for voltage, 4.88 μA for current). Accuracy: ±0.5% of full scale at 25 °C, with temperature drift ±0.02%/°C. Settling time is 2 ms for voltage and 3 ms for current. The outputs are protected against short circuits to ground or power supply. An output hold function is available: when the PLC goes into STOP mode, the outputs can either hold last value or revert to a preset default (user‑configurable via DIP switch).
Data Format and Addressing
The ARM21 occupies two output words in the PLC’s I/O memory, one for each channel. Data can be written as binary 0‑4095 (12‑bit right‑justified) or as BCD 0‑2000 (selectable via DIP switch). To set 5.00 V, write 2048 (binary) or 1000 (BCD). The module also has a status input word that reports output validity and external power status.
Power and Isolation
The module requires an external 24 V DC power supply (350 mA maximum), typically sourced from a CQM1‑IPS02 or an external industrial power supply. This external power is isolated from the PLC backplane (isolation voltage 500 V AC). Each output channel is also isolated from the other, preventing ground loops. The analog output circuits are protected by a replaceable fuse (F1 for output 1, F2 for output 2, rated 100 mA).
Installation and Configuration
Mount the ARM21 to the right of the CPU or other expansion units. Use the DIP switches on the front to select: output range (voltage or current) per channel, data format (binary/BCD), and hold/clear behavior on STOP. Wiring uses a removable 10‑pin terminal block (M3 screws). For voltage output, connect the load between V OUT and AGND; for current, connect between I OUT and AGND. A shield connection is provided for each channel.
Programming Example
In CX‑Programmer, move the scaled analog value to the output word (e.g., MOV #800 to 2001 for 5.00 V if using 0‑10V range). Scaling from engineering units: if a flow controller requires 4‑20 mA for 0‑100%, use the formula: output value = (percentage / 100) × 4095. The module’s error flag can be monitored to detect overloads or external power failure.
Applications
Common uses: controlling a VFD speed reference, positioning a proportional hydraulic valve, generating a torque reference for a servo amplifier, or driving a pen recorder. Two channels allow for dual‑axis or combined pressure/flow control in small process systems.
