Yamatake SDC35/36 Controller Application Guide

Yamatake SDC35/36 Single Loop Controller Engineering Application and Debugging Manual

In the field of industrial process control, single loop digital regulators are still the main instruments for temperature/process control in heat treatment furnaces, plastic machinery, environmental testing chambers, packaging equipment, etc., due to their high reliability, fast response, and easy operation. The DigitroniK series SDC35/36 controller from Yamatake (now part of Azbil Group) in Japan has won a wide market with its compact design (panel depth of only 65mm), high precision (± 0.1% FS), and advanced PID algorithm "Rational LOOP+Just FITTER". This controller supports thermocouples RTD、 Multiple range inputs such as current and voltage, can be freely combined with up to two control outputs (relay, voltage pulse, continuous voltage, current), and can be optionally equipped with event output, CT input, etc DI、 Remote Set Point (RSP) and RS-485 communication. This article will provide a comprehensive engineering practice guide for automation engineers, covering hardware selection, installation and wiring, parameter tuning, event diagnosis, and maintenance troubleshooting.

Product positioning and core advantages

The main difference between SDC35 and SDC36 lies in their external dimensions (48 × 48 mm for SDC35 and 96 × 96 mm for SDC36) and differences in some I/O points, but their core control performance is completely consistent. Its prominent features include:

Ultra thin design: The depth behind the panel is only 65mm, and the thickness of the front panel is 5mm, suitable for control cabinets with tight space.

High precision and fast sampling: With an indication accuracy of ± 0.1% FS and a sampling period of 100ms, it can capture rapid temperature fluctuations.

Multi range input: The same device can be freely set to TC (26 types including K, J, E, T, R, S, B, N, etc.) RTD（Pt100、JPt100）、 DC current (0-20mA, 4-20mA) or DC voltage (0-5V, 1-5V, 0-10V, etc.) greatly simplifies spare parts inventory.

Advanced PID algorithm: Rational LOOP combined with Just FITTER technology effectively suppresses overshoot, responds quickly to external disturbances, and supports up to 8 sets of PID parameters.

Flexible output combination: Control outputs 1 and 2 can be selected from relays (SPST or SPDT), voltage pulses (SSR drive), currents (0-20mA/4-20mA), or continuous voltages (0-5V/1-5V/0-10V), respectively, to achieve dual output control for heating/cooling.

Rich auxiliary I/O: up to 3 event relays, 2 CT (current transformer) inputs, 4 digital inputs (DI), remote set point (RSP) inputs, and RS-485 Modbus communication.

Intelligent loading software: Parameter configuration, real-time monitoring, and data recording are carried out through the SLP-C35 software package (Smart Loader Package).

Detailed explanation of technical specifications

2.1 Input (PV) specifications

Project parameters

Input type thermocouple (K, J, E, T, R, S, B, N, PLII, Wre5-26, Ni NiMo, PR40-20, DIN U/L, gold iron chromium nickel, etc.), RTD (Pt100/JPt100), DC current (0-20mA/4-20mA), DC voltage (0-10mV, 0-10mV, 0-1V, 0-5V, 1-5V, 0-10V)

Sampling period of 100 ms

Input impedance voltage input ≥ 1M Ω; current input ≤ 100 Ω

Broken thermocouple/RTD: upper limit beyond range+AL01 display; Voltage/current: can be set as lower or upper limit, please note that wire breakage cannot be detected within the range of 0-10V and 0-20mA

Cold end compensation accuracy ± 0.5 ℃ (23 ± 2 ℃ environment), ± 1.0 ℃ (15-35 ℃), ± 1.5 ℃ (0-15 ℃ or 35-50 ℃)

Indication accuracy ± 0.1% FS ± 1 digit; The negative temperature range of the thermocouple is ± 0.2% FS ± 1 digit (23 ± 2 ℃)

Engineering points: For B-type thermocouples (0-1800 ℃), the accuracy is ± 4.0% FS below 260 ℃, so B-type thermocouples should not be used in low-temperature areas; The accuracy of R/S type below 100 ℃ is ± 0.2% FS.

2.2 Control output specifications

The controller provides up to two control outputs (depending on the model), with optional types:

Applicable scenarios for output type specifications

Relay contact (SPST) control output 1 (NO side): 250Vac/30VDC, 3A (resistive), lifespan ≥ 50000 times; Control output 2 (NC side): 1A, lifespan ≥ 100000 times, directly drive contactor and heater

Motor driven relay dual circuit relay (forward and reverse), 250Vac 8A, used for electric valve position control and valve position adjustment

Voltage pulse 19Vdc ± 15%, internal resistance 82 Ω, maximum 24mA, minimum pulse width 1ms (period ≤ 10s) or 250ms (period>10s) to drive solid-state relay (SSR)

Current output 0-20mA/4-20mA, load ≤ 600 Ω, accuracy ± 0.1% FS, resolution 1/10000, driving thyristor power regulator and frequency converter

Continuous voltage 0-5V/1-5V/0-10V, load ≥ 1k Ω, accuracy ± 0.1% FS driven analog input actuator

Attention: When using voltage pulse output, the cycle time can be set within the range of 0.1-20 seconds (≤ 10s cycle) or 5-120 seconds (>10s cycle) to match different types of SSRs.

2.3 Auxiliary functions

Event output: up to 3 independent relay contacts (250Vac/30VDC, 2A). Programmable for PV high/low limit, deviation high/low limit, MV high/low limit, Loop Diagnosis 1/2/3, timer, RSP status, AT status, etc.

External Digital Input (DI): Up to 4 points, assignable functions include: SP number switch, PID group switch, RUN/READY switch, AUTO/MANUAL switch, LSP/RSP switch, AT start/stop, SP ramp enable, PV value hold, timer start/stop, etc.

Current Transformer Input (CT): 2-point, paired with QN206A (aperture 5.8mm) or QN212A (12mm) current transformers, to detect heater load current (0.4-50A). Can be achieved:

When the control output is turned on: detect heater disconnection or overcurrent.

When the control output is OFF: detect SSR short circuit (still current flowing).

Remote Set Point (RSP): It can achieve external control by inputting set points from PLC or upper computer through 0-20mA/4-20mA or 0-5V/1-5V/0-10V.

Communication interface: RS-485 (Modbus RTU, slave), baud rate 4800-38400, up to 31 units in a network; There is also a dedicated Loader interface (19200 bps) connected to SLP-C35.

2.4 Power Supply and Working Environment

Power supply: 85-264Vac (50/60Hz) or 24Vdc model (selected when ordering), power consumption ≤ 12VA.

Working temperature: 0-50 ℃ (upper limit is 40 ℃ when installed horizontally), humidity 10-90% RH, no condensation.

Insulation withstand voltage: 1500Vac/1min between the power supply end and the secondary end, insulation resistance ≥ 10M Ω (500Vdc).

External dimensions: SDC35 is 48 × 48 × 65mm (panel opening 45 × 45mm), SDC36 is 96 × 96 × 65mm (opening 92 × 92mm).

Key points of installation and wiring engineering

3.1 Panel Opening and Installation

Use a dedicated installation bracket (included with the package). Insert the controller into the opening from the front, cover the bracket from the back, and tighten the screws until there is no gap - excessive tightening may cause deformation of the housing.

When three or more units are installed horizontally side by side, the upper limit of the ambient temperature is reduced to 40 ℃, and attention should be paid to heat dissipation.

3.2 Terminal isolation and grounding

The internal isolation structure of SDC35/36 is as follows (see manual diagram):

The power supply, control output 1/2, CT input, MFB input, relay output, RS-485, RSP input, etc. are isolated from each other (solid line part).

The digital input (DI1-4) is not isolated from the internal circuit (dashed part), and attention should be paid to common mode voltage.

Grounding: The grounding terminal of the power terminal must be reliably connected to the protective earth (PE) to reduce common mode interference.

3.3 Anti noise measures

The controller is sensitive to noise on the power and signal lines, especially when there are contactors, SCR power regulators, high-frequency welding machines, and other equipment on site.

Recommended measures:

Parallel CR filter (Yamatake model 81446365-001, or Matsuo 953M50033311) at the power input end.

The power cord should be as short as possible and laid separately from the signal line (with a spacing of ≥ 50cm), and should not be threaded into the same cable tray or metal tube.

The input signal lines (TC, RTD, 4-20mA) use shielded twisted pair cables, with the shielding layer grounded at one end (controller side).

The CT input line should be twisted and kept away from the power line.

3.4 Precautions for CT wiring

Open circuit is strictly prohibited on the secondary side of CT, otherwise high voltage danger may occur. When the controller is not in use, be sure to short-circuit the CT input or connect it to the controller first.

Measurement range 0.4-50A rms (50/60Hz). The transformation ratio is fixed at 800:1 (such as QN206A rated input 50A, output 62.5mA, but the controller is compatible with 0-50mA). Attention: The internal sampling resistor of the controller is fixed and does not require external connection.

Minimum ON time requirement for detection: For wire breakage detection, the output ON time should be controlled to be ≥ 0.3s; for SSR short circuit detection, the output OFF time should be controlled to be ≥ 0.3s.

Parameter setting and tuning

4.1 Using Smart Loader Package (SLP-C35)

SLP-C35 is a PC software (supporting Windows) that connects to the Loader interface on the front of the controller via a dedicated cable (19200 bps). The functions include:

Parameter Read Write and Backup

Real time trend monitoring (PV, SP, MV)

Automatic Tuning (AT) Wizard

Event configuration, DI allocation

Copying parameters of multiple controllers

First use steps:

Install the software and connect the cable (2m dedicated line).

After power on, the software automatically recognizes the device.

Read the current parameters and save them as a project file.

Modify input type, range, control mode, PID value, etc. as needed.

Write into the controller and perform functional testing.

4.2 PID Auto tuning

SDC35/36 adopts a Limit Cycle to automatically tune PID parameters. Users can choose from three control features:

Standard: Balance response and stability.

Fast disturbance response: responds faster to load changes, but may experience slight overshoot.

Reduce up and down fluctuations: more suitable for objects with high inertia and low overshoot.

Operation:

Stabilize the PV near the working point.

Set AT startup (can be done through DI or parameter AT=1).

The controller will automatically adjust the output step change, generate oscillations, and record the limit period.

After the tuning is completed, the PID parameters are automatically stored in the current group.

Notes:

When self-tuning, the final control components (heater, SSR, contactor, etc.) must be powered on simultaneously or in advance with the controller, otherwise they cannot respond correctly.

During the tuning process, it is prohibited to switch between RUN/READY or power off.

4.3 Just FITTER Technology

Just FITTER is an overshoot suppression algorithm that dynamically adjusts the output by monitoring the PV rise rate. Users can set the "overshoot suppression coefficient" (0~100), the larger the coefficient, the stronger the suppression. For processes that do not allow overshoot (such as biological cultivation and plastic extrusion), it is recommended to set it to 50-80.

4.4 Multiple sets of PID and SP numbers

The controller can store up to 8 sets of PID parameters and 8 set values (SP numbers). It can be switched online through DI input or communication. Suitable for producing equipment with multiple varieties and different temperature ranges.

Common troubleshooting and maintenance

6.1 PV display abnormality (---- or 9999)

Possible reasons: sensor disconnection, incorrect input type setting, and failure of cold end compensation.

Solution: Check the TC/RTD wiring and measure the resistance or millivolt value with a multimeter. Enter the settings menu to verify the input type (such as K-type Pt100）。 If it is a thermocouple, check the cold end compensation method (internal/external).

6.2 Controller does not output, OUT indicator light does not light up

Possible reasons: READY mode (parameter rEAdY=1), or manual mode with MV=0, or PID parameter causing output to be 0.

Solution: Check the status indicator lights "man" (manual) and "rdy" (ready). Set rEAdY to 0 or switch to AUTO mode.

6.3 Heater disconnection alarm, false alarm or missed alarm

Possible reasons: CT ratio setting error, improper current threshold, insufficient minimum ON/OFF time.

Solution: Use a clamp gauge to measure the heater current and compare it with the displayed value on the controller. Adjust the alarm threshold (it is recommended to set it to 50% of the normal current). Ensure that the control output ON time is ≥ 0.3s (if the cycle time is too short, the cycle can be increased).

6.4 RS-485 communication failure

Possible reasons: duplicate address, inconsistent baud rate, unconfigured terminal resistance, reversed wiring polarity.

Solution: Check station number (1-31), confirm that the baud rate, data bits, and parity bits of the master and slave stations are consistent. Add 120 Ω terminal resistors at both ends of the bus. SDC35/36 uses a three wire system (+, -, SG), do not connect SG to the ground.

6.5 Self tuning does not converge or oscillates violently

Possible reasons: object nonlinearity, large actuator dead zone, insufficient sampling period.

Solution: Manually adjust the PID or reduce the output cycle. For objects with large lag, the integration time can be increased.

Maintenance and lifespan management

Regular calibration: It is recommended to use a standard signal source to check PV accuracy every year, especially for cold end compensation.

Relay lifespan: The electrical lifespan of the control output relay (3A/250Vac) is approximately 50000 cycles. For frequent on-off situations, voltage pulse output+SSR or external solid-state relay should be used.

Spare parts: After long-term shutdown, at least one spare machine of the same model should be retained for quick replacement. When replacing, use SLP-C35 to upload the original parameters and download them to the new machine.

Cleaning: Wipe the panel with a soft cloth and avoid using organic solvents.

Typical application cases

8.1 Injection molding machine barrel temperature control

Configuration: SDC36, K-type thermocouple input, voltage pulse output drives SSR heating. Heating/cooling dual output (the second output is a relay controlled cooling fan).

PID parameters: Self tuning selection of "fast disturbance response" effectively suppresses temperature fluctuations caused by feeding.

Event: PV high limit alarm (to prevent overheating of the material cylinder), Loop Diagnosis 2 detects heater disconnection.

8.2 Constant temperature and humidity chamber (environmental test)

Configuration: SDC35, Pt100 input, 0-10V output to drive the power regulator for heating, and another 4-20mA output to drive the humidifier.

Multiple sets of PID: one set each for the low temperature section and high temperature section.

RSP input: PLC provides program curve (via 4-20mA), and the controller locally executes PID.

8.3 Food sterilization kettle

Configuration: SDC36, dual input for temperature and pressure (via linear input 4-20mA transmitter). The control output is a relay driven steam valve.

Event: Deviation alarm, SP slope status indication.