CJ2M-MD212 Pulse+Direction Configuration for Yaskawa Servo Drives

Application Overview

The CJ2M-MD212 pulse I/O module expands a CJ2M PLC with two independent high-speed differential pulse outputs suitable for commanding Yaskawa Sigma-series servo drives in pulse + direction mode. The MD212 produces RS-422 (line driver) signals at up to 500 kHz with built-in origin search, trapezoidal and S-curve acceleration profiles. Common target drives include Sigma-3 (SGDV), Sigma-5 (SGDMV), Sigma-V (SGDV), and Sigma-7 (SGD7S) families. This reference covers a typical 1- to 2-axis application where a CJ2M rack is populated with MD212 (pulse I/O), MAD42 (analog I/O for servo monitoring or process trim), OD212 (DC output for servo /S-ON, /ALM-RST, /P-CL, /N-CL), and ID211 (DC input for proximity, limits, home, and RUN commands).

The MD212 is the correct choice over the related CJ2M-MD211 module whenever the Yaskawa drive is wired for 5 V differential (line receiver) pulse command input, which is the factory default on Sigma-3 through Sigma-7. The MD211 (24 V NPN open-collector, 100 kHz) only suits low-rate applications where the drive has been repurposed for open-collector input via jumper change on CN1.

This reference does not cover:

• MECHATROLINK-II or MECHATROLINK-III fieldbus, which would require a CJ2M with the CJ1W-MCH71 or CJ1W-NCF71 module instead.
• Torque or velocity control modes of the Yaskawa drive, which require setting Pn000/Pn200 to values other than the position-control case presented here.
• Continuous contouring, registration, or cam profiling, which require additional CJ2M CPU firmware options.

Module Selection: CJ2M-MD211 versus CJ2M-MD212

CJ2M-MD212 Electrical and Timing Specifications

Front-Panel Indicators and Module Diagnostics

A PULSE LED stuck on with the drive motor energised indicates either a configuration error (PLC Setup mismatch) or hardware failure of the MD212 line driver IC. Always capture initial LED states at first power-up and retain them in the machine's commissioning dossier for comparison against field fault reports.

Rack Layout, Power Budget and Companion Modules

The MD212 occupies one CJ-series slot. Its 16 I/O words are reserved for special I/O and are not usable for general digital or analog I/O. The CJ2M stack-up for a Yaskawa pulse-command axis typically combines:

• Slot 0: CJ2M-CPU11/12/13/14/15 (or higher). The CPU models with built-in pulse outputs (CPU22 through CPU35) include 100 kHz outputs that may be used in parallel or reserved for a different axis.
• Slot 1: CJ2M-MD212 (pulse + direction to two Yaskawa amplifiers).
• Slot 2: CJ2M-ID211 (DC 24 V input, 16 points) — proximity, limits, home, /S-ON feedback, /ALM contact.
• Slot 3: CJ2M-OD212 (DC 24 V output, 16 points) — drive /S-ON, /ALM-RST, /P-CL, /N-CL, and brake release.
• Slot 4: CJ2M-MAD42 (analog I/O: 4 inputs + 2 outputs, 16-bit) — torque monitor, follower trim, or process setpoint.

Use CX-Programmer's I/O Table utility to drop these into the rack and confirm the auto-allocation. The MD212 occupies a 16-word block typical of CJ2M special I/O modules. Confirm the backplane 5 V budget:

I_total = 220 + 80 + 110 + 220 = 630 mA reserve for cooling expansion

Most CJ2M CPUs source 2.0 to 2.5 A on 5 V, leaving ample margin. Failure to budget causes intermittent MD212 ERC events during high-frequency bursts when the backplane voltage momentarily sags.

Yaskawa Sigma Pulse Command Interface (CN1)

Sigma-3 (SGDV), Sigma-5 (SGDMV), and Sigma-7 (SGD7S) all share a 50-pin CN1 control interface. The following pins apply to pulse-command position control. Always consult the specific SERVOPACK manual for the exact pinout, as some models relocate signals on CN2 or add a CN3 second encoder port.

Differential Wiring Standards and Topology

Use a shielded, twisted-pair cable such as Omron XW2Z-100J-F1 or a UL-listed AWG-24 shielded cable with dedicated twisted pairs. The PULS pair and SIGN pair must each be a single twist; do not interleave PULS lines with SIGN lines.

Wiring Rules

1. Twist PULS+ with PULS-; twist SIGN+ with SIGN-. Maintain ≥ 1 twist per inch (5 twists per 100 mm).
2. Connect the cable shield at the PLC enclosure end only. Cut the shield short and tape it off at the drive end, or use a Yaskawa CN1 backshell that floats the shield from the drive chassis.
3. Ground the MD212 24 V return and the drive CN1 PGND to the same panel protective earth (PE) bus to avoid common-mode shift.
4. Maintain ≥ 50 mm separation between the pulse cable and any VFD motor cable. Cross at 90° only if intersection is unavoidable.
5. Use a Yaskawa CN1 connector housing (JAE part or equivalent) rated for 50 positions; pin contacts must accept AWG-26 to AWG-24.
6. Twist /S-ON and /ALM-RST as a third pair in the same overall cable jacket, but route that pair in a separate foil shield to keep drive-side logic noise out of the pulse lines.

CX-Programmer PLC Setup for Pulse + Direction

Open CX-Programmer 9.x or later, connect to the CJ2M CPU, and double-click the Settings folder. The Pulse Output 0 and Pulse Output 1 entries control the MD212 axis-0 and axis-1 behaviour. Configure each entry as follows:

1. Output type: set to "Pulse + direction (signed)" for both axes in use. Disabling the unused axis releases the SCPU resource.
2. Starting frequency: enter a value between 0 and 50,000 Hz. Typical: 1,000 Hz to avoid step-out on a heavily-loaded axis at low speed.
3. Acceleration/deceleration pattern: choose "Trapezoidal" (constant accel) or "S-curve" (jerk-limited). S-curve reserves ~10 % extra of trapezoidal time but reduces wear on belts, couplings, and rack-and-pinion axes.
4. Origin search method: choose 0, 1, 2 or 3 per the CJ2M Software User's Manual. Method 2 (proximity + encoder-Z origin search) is most common for rotary SERVOPACK encoders with a Z-phase marker pulse.
5. Origin search high speed: typical 50,000 Hz approach speed.
6. Origin search proximity speed: typical 10,000 Hz slow acquisition speed.
7. Origin search compensation value: leave at 0 unless a known mechanical offset exists between the origin marker and the desired home position.
8. Save the project, transfer to the PLC, switch PROGRAM → RUN, and confirm the MD212 RDY LED is steady green.

Special I/O Allocation and Internal Flags

For a CJ2M CPU with the MD212 in slot 1, the CX-Programmer I/O Table utility assigns the first base address automatically. Verify the actual base with the online I/O Table view. The default for Slot 1 is CIO 0 (special I/O area). The high-speed counter / pulse output area overlaps with the built-in CPU pulse-output area; use the following special flags:

The addresses assume the standard CX-Programmer allocation for a CJ2M CPU with MD212 in slot 1. If the actual allocation differs, open CX-Programmer's Memory View and verify each address before writing ladder that depends on it.

Ladder Code: Continuous Speed Output (SPED + ACC + INI)

Use SPED(885) for continuous speed, ACC(888) for trapezoidal acceleration, and INI(880) for an explicit stop. The example below accelerates axis 0 at 250 pulses per 4 ms (≈ 62.5 kHz/s) up to 50 kHz in the forward direction.

| W0.00       SPED(885)  -- pulse output 0
|--+--)/--+--| P |--- Control Word: P = 0000 (axis 0, no accel)
|              |     Frequency: D100   = 50000 (target Hz, 32-bit)
|              |     Output port: D102   = 0 (CW direction)
|              |     Mode:       D104   = 0 (independent)
|
| W0.01       ACC(888)  -- axis 0
|--+--)/--+--| P |--- Control Word: P = 0000 (axis 0)
|              |     Accel rate:  D110   = 250 (pulses/4 ms)
|              |     Decel rate:  D112   = 250 (pulses/4 ms)
|
| W0.02       INI(880)  -- stop axis 0 immediately
|--+--)/--+--| P |--- Control Word: P = 0000 (axis 0)
|              |     Mode:        D120   = 5 (Pulse Output Stop)

Rising edge on W0.00 triggers SPED to issue axis-0 pulses and the A281.08 active flag rises until INI(880) is executed or the SPED instruction is interrupted by another instruction writing the same axis. The MD212 PULSE 0 LED will sync to the pulse stream at 50 kHz and appear nearly solid for typical viewing angles.

Ladder Code: Trapezoidal and S-Curve Positioning (PLS2)

PLS2(887) outputs a defined pulse count at a defined target frequency with independent accel and decel. The example issues an absolute move of 200,000 pulses at 100 kHz with equal 500-pulses-per-4 ms accel and decel rates.

| W0.10       PLS2(887)  -- axis 0 absolute move
|--+--)/--+--| P |--- Control Word: P = 0000 (axis 0)
|              |     Pulse mode:   D200    = 1 (absolute)
|              |     Target PV hi: D201    = 0
|              |     Target PV lo: D202    = +200000 (signed 32-bit)
|              |     Target freq:  D204    = 100000 (Hz)
|              |     Accel rate:   D206    = 500 (pulses/4 ms)
|              |     Decel rate:   D208    = 500 (pulses/4 ms)
|
|--( )---------|
| A281.08      PLS2 check
|--+--/----| END |       ; wait for axis-0 active flag to clear

Setting D200 = 0 selects relative mode (D201/D202 pulses from the current PV); D200 = 1 selects absolute mode (D201/D202 pulses from the origin). To enable S-curve motion, set the PLC Setup pulse-output pattern to "S-curve" for that axis. The PLC then handles the S-curve profile in firmware; the pulse count output remains the same but the accel/decel change-of-junction is smoother.

To verify PV at any time, use PRV(287) (High-Speed Counter PV Read) which captures both the 32-bit PV and the current output frequency in a single instruction. PRV is particularly useful for inch-mode manual moves and for confirming homed position before tool changes.

Origin Search and Homing Routine (ORG)

The ORG(889) instruction implements the CJ2M built-in origin search. It depends on four inputs wired to a high-speed input module such as the ID211:

• Origin proximity input (IN0): PNP proximity sensor mounted a few millimeters before the home position.
• Origin input (IN1): encoder Z-phase output from CN1 pin 23/24 (or a dedicated home limit switch for stepper/encoderless applications).
• CW limit (IN2) and CCW limit (IN3): hard overtravel limit switches wired fail-safe (N.C. contacts).

| W0.20       ORG(889)  -- axis 0 origin search
|--+--)/--+--| P |--- Control:    P = 0000 (axis 0)
|              |     Method:     D300   = 2 (proximity + Z)
|              |     Origin prox: input 0.04
|              |     Origin in:   input 0.05
|              |     CW limit:    input 0.06
|              |     CCW limit:   input 0.07
|
| A280.00     wait for ORG to release
|--+--/----| END |       ; A280.00 clears when ORG returns Complete
|
| A280.01     PV reset on completion
|--+--( )--( | )--- reset touch sensor W100.00

When ORG(889) completes, the MD212 sets the Pulse Output 0 PV to zero and the A281.10 PV-Zero flag rises. With a 23-bit absolute encoder on the Yaskawa motor and a proximity + Z origin sequence, the homed-position accuracy is one motor encoder count (i.e. 0.011° for a 23-bit 32768-count-per-turn motor), limited only by the mechanical repeatability of the home flag sensor.

Yaskawa Parameter Map and Electronic Gear Ratio

After wiring and CJ2M commissioning are verified, configure the SERVOPACK. The list below covers the common parameters required for pulse + direction operation. Always verify against the SERVOPACK manual for the specific model in use.

Electronic Gear Ratio Calculation

The electronic gear converts the incoming pulse train into motor shaft displacement using:

Motor displacement = Pn010 / Pn009 × Number of command pulses

Choose Pn009 first (typically the encoder resolution: 32768 for 23-bit). Then select Pn010 so that the load displacement per command pulse is a round engineering number.

Worked example 1 — linear ball screw: 5 mm pitch ball screw, 32768 c/rev encoder, target 0.01 mm per command pulse (500 pulses per motor revolution).

Pn009 = 32768
Pn010 = 32768 / 500 = 65.536 -> enter 65
Working displacement per pulse = 5.043 mm / 500 = 0.01009 mm
1 command pulse = 0.01009 mm linear travel

Worked example 2 — direct-drive rotary table: 3600 pulses per motor revolution desired.

Pn010 = 32768 / 3600 = 9.102 -> enter 9
Working displacement per pulse = 1/9 rev = 0.1111... deg
3600 command pulses = exactly 360 deg

Safety Integration, E-Stop, and Cycle-Time Considerations

Hardwired safety must not depend on the PLC scan time. Wire the drive Safe Torque Off (STO) inputs directly to the safety relay — do not pass them through the MD212 or through any CJ2M high-speed counter input. The drive will not develop torque while the STO loop is open, regardless of the pulse stream.

Cycle-time considerations:

• CJ2M-MD212 pulse output update rate is 4 ms (250 Hz). Maximum acceleration response is therefore a stepping of 65,535 pulses per 4 ms, matching the spec.
• PLC scan time at 5 ms combined with a 4 ms pulse-output update produces an end-to-end command latency of 9 ms worst case. The Yaskawa drive position-loop bandwidth (typically 100-200 Hz) absorbs this margin on most mechanical axes.
• For high-bandwidth registration or print-mark applications, route the registration trigger into the high-speed interrupt (MSKS instruction) of the CJ2M CPU rather than the periodic scan; the MD212 supports hardware-based interrupt registrations on input channels 0/1.
• If the calculated peak pulse rate exceeds 250 kHz, plan for S-curve acceleration or divide the move into multiple PLS2 segments to keep average pulse rates below 200 kHz. Sustained 500 kHz moves generate heat on the MD212 line drivers (see thermal caveat above).

Troubleshooting Matrix: Alarms and Diagnostics

When a Yaskawa alarm is observed, cycle control power only after clearing the alarm with the /ALM-RST input (CN1-44 pulse ≥ 120 ms, active-low). Cycling the main power without clearing causes the alarm to reappear and may corrupt the parameter checksum on drives older than firmware 32xx. Refer to the Yaskawa Sigma-7 documentation for the full alarm list and the dedicated servo-troubleshooting manual.

Verification and Commissioning Checklist

1. Confirm the MD212 RDY LED is steady green once the CJ2M CPU enters RUN. A flicker or constant red indicates a slot or power problem and the module must be reseated or replaced.
2. Set the SERVOPACK: Pn000 = 0, Pn200 = 0, Pn218 = 0, Pn219 = 0. Cycle main power to commit.
3. Use the digital operator (or SigmaWin) to confirm the parameter changes are stored. Verify encoder resolution reported back matches Pn009.
4. Issue a 100-pulse relative move at 1,000 Hz with SPED. Confirm the motor shaft rotates the expected angle, that the A560 error stop flag stays clear, and that PULSE 0 LED on the MD212 cycles visibly.
5. Issue a 10,000-pulse absolute move with PLS2 to test full closed-loop with the A281.08 active flag rising and clearing per the move window.
6. Trigger ORG(889) and verify the axis returns to the home position reproducibly to within one motor encoder count. Capture the resulting PV value with PRV(287).
7. Run a 24-hour continuous-rotation soak test at 60 % of the maximum pulse rate while monitoring motor winding temperature, drive heat-sink temperature, and MD212 ERC LED.
8. Document final Pn009/Pn010 gear ratio, PLC Setup accel/decel rates, CX-Programmer version, drive firmware revision, and digital operator password in the machine handover document.
9. Train the end-user on how to read the alarm list on the digital operator and how to retrieve it programmatically via the RS-422 Modbus maintenance interface.

Frequently Asked Questions