Omron CQM1H Programming Reference: Inverters, Encoders, PID, and Syswin 3.x

The Omron CQM1H family is a compact modular PLC that bridged the gap between the original CQM1 and the later CJ1 series. It is still in service in many installed machines, including dye-dosing skids, packaging lines, and textile machinery. This reference consolidates the field knowledge required to commission, fault-find, and extend a CQM1H rack that combines a CPU61, a Controller Link card, high-speed counter and pulse I/O inner boards, and 3G3MV Sysdrive inverters. The procedures, register maps, and scaling formulas below are written for a maintenance engineer who is comfortable with ladder logic and Boolean sequencing, but who is migrating from a GE Fanuc / SCADA background into the Omron programming environment.

1. CQM1H CPU Family Overview

The CQM1H is a backplane-free modular PLC: the CPU, up to two inner boards, and the I/O modules are mounted on a single base plate and connected through side-by-side connectors. The major CPU part numbers are CPU11, CPU21, CPU31, CPU41, CPU51, and CPU61. The CQM1H series page on ia.omron.com shows the full lineup and confirms the features described below.

The CPU61 used in the dye-dispensary prototype is the highest-spec CQM1H variant. It supports the full 15.2K-word program area, 6K words of data memory (DM 0000 to DM 6143), and 6K words of expansion memory (EM 0000 to EM 6143). The CPU61's two built-in serial ports are:

• Peripheral port — RS-232C on a mini-DIN connector, intended for Syswin/CX-Programmer programming, but it can also host a 1:1 NT-link to a PT.
• RS-232C port — DB-9 (XM2A-0901 type), supports Host Link, NT Link 1:N, 1:1, no-protocol, or Protocol Macro on the CPU61/51.

Both ports run independently. In the prototype described in the source field notes, the peripheral port is wired through an RS-422/232 converter to a status PC, and the second RS-232C port is unused at the network level. Because the converter is on the programming port, the station can be brought offline and re-flashed without disturbing any Controller Link traffic as long as the station is the only node dropped during the upload window. Hot-plug is not documented; treat the connector as live.

2. Power Supply and Backplane

The CQM1H uses the PA-series power supply that bolts to the left end of the rack. Three units are common in the field:

The PA203 budget for the prototype is tight: a CPU61 plus a CTB41, a PLB21, an SRM21-V1, and 4 ID212/OD214 modules plus a 3G3MV auxiliary supply all draw from the same 5 VDC rail. Before adding expansion, sum each module's published 5 VDC current from the CQM1H datasheet and keep margin under 2.5 A continuous.

3. Inner Board Architecture (CTB41, PLB21, CLK21, SRM21)

The CQM1H has two inner-board slots that are physically separate from the I/O bus. Each slot accepts one of a defined list of inner boards; the combination is fixed at purchase time. The four boards relevant to the dye-dispensary application are described below. Detailed I/O assignments are in the CQM1H Catalog (Cat. No. P033).

3.1 CTB41 — High-Speed Counter Board

The CTB41 is a 4-channel, 24 VDC high-speed counter. The maximum input frequency depends on the mode:

• Up/down, increment, or quadrature (×1) — 50 kHz
• Quadrature ×4 — 50 kHz
• Pulse + direction — 50 kHz

The four counters occupy fixed DM and IR areas. By default, the present values are in IR 200 to IR 207, and the comparison match bits are mapped to AR 04 to AR 07. Reset, gate, and preset words are in IR 208 to IR 215. The CN1 connector on the CTB41 is a high-density D-sub; field wiring for the dye-carousel encoder distributor motor lands here.

Encoder scaling for a CTB41: if a 2000-pulse-per-revolution incremental encoder is mounted on a 40:1 gearbox driving the vertical trolley, the pulse rate at full speed is:

f = 2000 ppr × 40 × n_rpm / 60

For n = 1500 rpm, f = 2,000,000 pulses/second. That is well above the 50 kHz ceiling, so either the resolution must be reduced, the gearbox ratio changed, or the CTB21 (500 kHz) inner board should be specified instead. Always check the mechanical top speed against the counter's published rate before commissioning.

3.2 PLB21 — Pulse I/O Board

The PLB21 is a 2-channel pulse I/O inner board. Each port (CN1 and CN2) can be configured as a pulse output, a high-speed counter input, or a combined positioning axis with home, overtravel, and near-home inputs. The PLB21 supports the standard pulse-train frequencies of 10 Hz to 100 kHz in 1 Hz steps, which it generates from the CPU61 scan or from a fixed acceleration ramp.

In the dye-dispensary prototype:

• CN1 — Pulse I/O channel 1, controlling the tilt-rotation motor via the 3G3MV inverter. Used in pulse-output + direction mode.
• CN2 — Pulse I/O channel 2, controlling the vertical trolley that lifts hoppers from the carousel.

Relevant IR/DM mapping for the PLB21 (default port assignments):

To move channel 1 to a target of 12,500 pulses with a 1 kHz base, 50 ms acceleration ramp, and origin return enabled, set:

DM 1000 = 1000      ; base frequency (Hz)
DM 1001 = 12500     ; target position (pulses)
DM 1002 = 50        ; accel/decel time (ms)
DM 1003 = 0010 Hex  ; bit 4 = origin search enable, bit 1 = mode select
AR 02.00 = ON       ; PLS1 output trigger (rising edge)

3.3 CLK21 — Controller Link Inner Board

The CLK21 is a Controller Link module set to 2 Mbps over shielded twisted pair. In the prototype, the network card lives in inner-board slot A. The board binds the local CQM1H to a higher-level PLC (C200Hα or CV-series) or to a SCADA gateway, depending on the project. Up to 32 nodes can sit on a single Controller Link segment, and the network supports data-link tables for cyclic data exchange plus message services for one-shot reads/writes.

The data-link areas (allocated in the CPU61) are normally:

• Area 1 (LR 00 to LR 63) — 64 words
• Area 2 (LR 64 to LR 99) — 36 words

If a node number 2 on the network has a single 16-word output block, the local CQM1H reads it from DM 1000 to DM 1015 (default) by writing the routing table and the link refresh parameters. The exact layout is project-specific; confirm the originator's datasheet before editing.

3.4 SRM21-V1 — High-Speed / Long-Distance Comms Board

The SRM21-V1 inner board is the CompoBus/S master or a long-distance RS-485 Host Link board, depending on the firmware suffix. The V1 suffix indicates the CompoBus/S (DeviceNet predecessor) configuration. It allows the CPU61 to communicate with remote I/O terminals (SRT2 series) over a 750 kbps trunk up to 100 m, or with 93.75 kbps long-distance trunks up to 500 m. Allocation of CompoBus/S I/O starts at IR 050 to IR 099 by default and can be remapped in the Syswin PLC Setup.

4. I/O Expansion Modules

Standard CQM1H I/O modules are inserted to the right of the inner boards and the CPU. The dye-dispensary rack uses the following modules:

5. 3G3MV Sysdrive Inverter Integration

The Omron 3G3MV Sysdrive is a 200 V or 400 V class general-purpose V/f inverter with ratings from 0.1 kW to 7.5 kW. The series supports a digital operator, Modbus RTU (RS-485), CompoBus/S, and an analog reference input. The 3G3MV product family lists the full range and the corresponding user manual (I528-E2).

In the dye-dispensary prototype, three 3G3MV inverters are wired in parallel, one per axis: vertical trolley, cutting-tool release, and tilt-rotation motor. All three inverters share the same 3 × 240 V 3-phase supply and are configured for V/f control with 240 Hz maximum output frequency. Their direction and run signals are wired to outputs of the PLB21 inner board or the OD214 module; the speed reference is fixed by parameter n25 in many cases, but the inverter can also accept a 4–20 mA signal from an analog output (the CQM1H has no built-in analog; a DA003 or DAM002 module is added when an analog loop is needed).

5.1 Inverter Parameter Map

5.2 Wiring the 3G3MV to a PLB21 Channel

The PLB21 pulse output is normally used to step a servo amplifier, but the dye-dispensary prototype uses the pulse train as a position reference for a 3G3MV in follower mode. In that case, the inverter must be set to:

n01 = 3   ; Modbus RTU control
n02 = 2   ; Frequency reference from serial
n150 = 5  ; RS-485 baud 9600
n151 = 0  ; Data 8, no parity, 1 stop
n152 = 1  ; Modbus node 1

Alternatively, leave n01 = 1 (terminal control) and use the analog reference plus a fixed-direction digital. Both methods are valid; Modbus gives access to all parameters, while terminal control is easier to fault-find on the bench.

5.3 Common 3G3MV Faults

6. Encoder Integration via the CTB41

The encoder for the dye-carousel distributor motor lands on CN1 of the CTB41 inner board. Wire it as an incremental quadrature channel with the 24 VDC supply sourced from the PA203 26 VDC rail (or from a separate DIN-rail power supply if the encoder draws more than 100 mA). The wiring for channel 0 is:

Set the Syswin PLC Setup for the CTB41 to:

Inner board 1: CTB41
Channel 0: quadrature x4
Range: 0 to 9999 (16-bit, no reset)
Output compare 0: 4800 counts (1 trolley revolution)

The count of 4800 for one trolley revolution assumes a 1200-ppr encoder with 4× decoding. To convert the raw count to a real-world unit (centimeters of vertical travel), multiply by the linear distance per pulse:

unit_per_pulse = lead_screw_pitch / (encoder_ppr × gear_ratio × 4)
real_distance = present_value × unit_per_pulse

For a 20 mm pitch, 1:1 ratio, 1200 ppr encoder, unit_per_pulse = 0.00417 mm/count. To move 50 mm, the target = 50 / 0.00417 ≈ 12,000 counts.

7. PID Control on the CQM1H

The CQM1H does not include a dedicated PID instruction. Closed-loop control is implemented either in ladder using the PID-A or PID-B instruction set, or in a loop built from arithmetic instructions (APR, SUB, MUL, DIV) with a periodic interrupt. The PID-A instruction in the CQM1H computes the MV (manipulated value) at the scan time or at a fixed scheduled interrupt; the PID-B variant uses 32-bit set point, process variable, and bias. Both instructions need their parameters stored in contiguous DM words.

7.1 PID-A Parameter Block (8 words)

If the dye scale is read by an analog input module and the result is stored in DM 2000 as a BCD value from 0 to 1000 (= 0.0 to 100.0 g), the PV is then DM 2000. The set point for a 25.00 g dose is DM 2010 = 250.

7.2 Scaling a BCD Analog Input to Engineering Units

A 0–10 V input from a load cell amplifier mapped to a 0–1000 raw count gives the following scaling formula:

EU = (raw - raw_offset) × (EU_span / raw_span)

For a 0.01 g resolution required by the dye spec, choose a load cell with a full-scale output of 50 g and an amplifier gain of 200 ×, so the raw input swings the full 0–10 V over 0–50 g. Then 1 raw count = 0.05 g, and the 0.01 g target is approximately 0.2 raw counts — well below the 12-bit resolution. In that case a 16-bit analog input module such as the AD101 is required.

7.3 Anti-Windup and Bumpless Transfer

Set TI = 0 to start with P-only control for first tuning, and confirm that the MV clamps work before introducing I. When switching from manual to auto, write the current MV to the bias word (offset +6) before enabling the instruction; otherwise a step in MV will hit the process and ring the loop.

8. Syswin 3.x Programming Environment

Syswin 3.x is the original Windows-based programming tool for the CQM1, C200H, and C200HS families. It supports on-line editing, I/O monitoring with force, and full task-based program structure. Newer CX-Programmer 9.x still opens and saves CQM1H programs, but Syswin 3.x is still used on many OEM machines because the OEM program was archived in SWS or MEM format. Syswin 3.x is compatible with the CPU61 in either peripheral-port or RS-232C-port modes.

To go on-line to the CPU61 from Syswin:

1. Connect the programming cable (CQM1-CIF01 + XW2Z-200S-CV or the XW2Z-070 host link cable) to the peripheral port or the RS-232C port.
2. In Syswin, choose PLC > Online > Connect; select Host Link for RS-232C port, or Peripheral Tool for the peripheral port.
3. Match the baud rate: peripheral port is fixed at 9.6 kbps; RS-232C is settable in the PLC Setup (default 9.6 kbps, 7-E-2).
4. Click Transfer from PLC to read the program, then Online Edit > Monitor for live ladder.

For force operations, use the Force > Set dialog. Note that the force is a one-shot register set; restarting the PLC clears all forces. Document any forced bit in the project hand-over folder because it can haunt a maintenance team months later.

9. Controller Link Networking

The CLK21 supports data-link areas of up to 64 words per node. For a small SCADA gateway, the CQM1H is the originator and the SCADA is a target. The default data-link table is enabled from the Syswin PLC Setup, Network tab, with the following minimum configuration:

The data-link refresh is asynchronous to the scan. When the SCADA expects a coherent snapshot, latch the data into a local DM block on a CQM1H periodic interrupt task, and only release the latch after the snapshot is consistent. A single-node outage on Controller Link stops data-link refresh for the entire segment; plan a watchdog that flags the loss in the local PLC.

10. Distributed Control Architecture

Many Omron installations use a small CV-series or CJ2 PLC as a supervisory controller and a string of CQM1H stations as local cell controllers. The two-way communication between them uses:

• Controller Link (cyclic data link, default 64 words per node)
• SEND(90) / RECV(98) instructions for event-driven messaging (up to 2012 bytes per message)
• CMND(??) instruction for FINS commands (read/write across the network, all PLCs from the same vendor)

The recipe for adding a new CQM1H to an existing Controller Link segment is:

1. Set the rotary switches on the CLK21 to the new node number (1 to 32).
2. Pull the data-link table into Syswin, add the new node, and upload the new table to all nodes on the network.
3. Power the new node last; otherwise a power-on surge can knock the existing segment off-line.
4. Confirm the new node appears in the routing table of every other node (Syswin > Network > Routing Table).

11. AREL (Stack-Based Sequencer) Programming

AREL is not part of the CQM1H toolset, but it is encountered in legacy Italian-built machinery, often in a wrapper around the Omron logic that exposes high-level sequencing. AREL (Assembly REal Language, in some references) is a stack-based virtual-machine language with the following structure:

• Operands are pushed onto the Boolean stack with PUSH / LOAD and combined with AND, OR, NOT.
• Comparators consume the top two operands and push a Boolean result (0 or 1).
• Accumulators are pre-named numeric registers; ACC1 is the default return register.
• Control flow is via IF NOT AR ... ; ... ; END_IF blocks that read the top of the stack as a Boolean.

The mapping to ladder is direct: each AREL PUSH I0.1 corresponds to a NO contact of the input bit, and each AND I0.2 corresponds to a series connection of the next contact. To follow the program, draw the ladder in parallel: each PUSH/AND/OR block becomes a vertical line of contacts, and each comparison block (==, <, >) becomes a coil or a transition to a function block. The most efficient way to reverse-engineer an AREL wrapper is to list every PUSH/AND/OR in execution order and look for the comparator at the end of each block — that comparator is the rung output.

12. Commissioning Procedure

The following procedure is field-proven for a CQM1H station similar to the dye-dispensary prototype.

1. Confirm the bill of materials. Verify the CPU61, PA203, CTB41, PLB21, CLK21, SRM21-V1, ID212, OD214, and three 3G3MV inverters are present and undamaged. Check for any burn marks on the PA203 connector and the 3G3MV DC bus capacitor vent cap.
2. Power-up checks. Apply control power with the main contactor off. Verify the CPU61 PWR LED is green and RUN is green or flashing; ERR should be off. Measure the 5 VDC and 26 VDC outputs of the PA203 with a calibrated meter; both rails should be within ±5 %.
3. Connect Syswin. Read the existing program and save it as a time-stamped backup before any change. Force a single input high in Syswin and verify the input LED on the ID212 module lights, confirming wiring polarity.
4. Bench-test the CTB41. Apply a hand-cranked encoder pulse or a 50 % duty-cycle signal generator at 1 kHz. The CTB41 present value in IR 200 should increment at the expected rate; if it does not, check the differential pair wiring and the 24 VDC supply on the encoder.
5. Bench-test the PLB21. With the inverter disabled, command a 1000-pulse move on PLB21 CN1 and verify the open-collector output. Use an oscilloscope on the output pins; missing pulses indicate a 24 VDC common issue or a faulty inner board.
6. 3G3MV commissioning. With the motor mechanically uncoupled, set n01 = 0 (keypad), run at 5 Hz, and confirm direction. Then re-couple, run at 5, 25, and 50 Hz, and measure motor current against nameplate FLA. n33 (electronic thermal) should be set to the motor FLA, not the inverter FLA.
7. Controller Link traffic. Use Syswin > Network > Data Link Monitor to confirm all configured nodes are alive. A single dead node shows as "---" in the status column.
8. PID tuning. Start with P-only (TI = 0), small PB, and a step set point. Increase PB until the loop oscillates, then back off by 50 %; introduce TI in 5 s steps and TD in 0.5 s steps. Record the final values in the project folder.
9. End-to-end test. Run the full dosing cycle with a representative 25.00 g recipe and verify the scale reads within ±0.02 g of the set point at the dispense end-of-cycle.

13. Troubleshooting Matrix

14. Field Notes and Caveats

• Document every change to a CQM1H program in a project log; the CPU61 does not have a revision history, and the only way to roll back is the last manual backup.
• Do not hot-swap any inner board; the high-density connectors are not rated for live insertion.
• The 3G3MV's electronic thermal (n33) must be set to the motor's nameplate full-load current, not the inverter's rated output.
• When the documentation is in a foreign language and the OEM is no longer reachable, photograph every terminal block and label it before disconnecting. Many dyes are corrosive; clean the block with isopropyl alcohol and re-tighten every screw.
• Inner boards consume both 5 VDC and 24 VDC; an under-spec PSU will cause brown-out faults that look like CPU errors. Always measure under load, not at idle.