Minco CT425 User Manual

CT425 PID Temperature Controller

Technical User Guide

CT425 PID Temperature Controller

Contents

CT425 PID Temperature Controller ....................... 2

Contents ............................................................. 2

Document Overview ........................................... 2

For More Information .......................................... 2

Introduction ............................................................. 1

Conventions ............................................................ 1

Installation ............................................................... 1

Mounting............................................................. 1

Wiring ................................................................. 1

Configuration .......................................................... 5

Status ................................................................. 5

General Settings ................................................ 5

Output Settings .................................................. 6

PID Settings ....................................................... 7

Document Overview

This document provides an overview of how to use the CT425 PID Temperature Controller.

For More Information

For more information on the contents of this document, please contact your local Minco representative.

Autotune ............................................................. 8

Data Logging ...................................................... 9

Submitting Settings .......................................... 12

General Usage ....................................................... 13

Status Indicators .............................................. 13

Output Behavior ............................................... 13

Errors ................................................................ 15

Multiple Units .................................................... 15

Bluetooth Low Energy (-BT Option Only) ......... 16

Frequently Asked Questions (FAQ) .................... 19

Using Thermistors ................................................ 19

Specifications ....................................................... 20

Inputs ................................................................ 20

Outputs ............................................................. 21

Communication ................................................ 21

Data Logger ..................................................... 21

General ............................................................. 22

Glossary ................................................................ 22

Introduction

The CT425 is a universal temperature controller that supports two platinum RTD inputs and three outputs. Thermistors are also supported to a limited extent. A 32 bit processor allows up to two PID loops to operate simultaneously at individually configurable loop rates up to 25Hz. An autotune feature generates PID coefficients, and all configurations are performed through a Windows application over a USB connection.

Each of the CT425’s three outputs (SSR, LVO, and Relay) has its own set of parameters that may be set independently of each other, including the use of either RTD input and On/Off, PID, or Alarm function. (PID available on SSR and LVO only)

AC powered models perform zero-cross detection to reduce switching noise on the SSR and LVO outputs.

Conventions

Different typestyles are used throughout this manual to make it easier to convey whether the text refers to a physical feature of the device, or if it refers to a general term.

A word or phrase with first letter capitalization (such as Relay Output) refers to a feature on the CT425 such as a terminal block connection or a function feature such as Alarm.

All other typestyles intend to reflect general terms.

Because of the Reverse Acting output feature, specific terms are used to indicate whether an output is in the closed or “on”

state, or if that output is in the active state regardless of the Reverse Acting Relay settings. If referring to whether an output is closed or providing voltage, “energize” will be used. If referring to if an output is in the active state, which ignores the Reverse Acting setting and only takes into account the intent of the algorithm, i.e. to turn a heater on when the temperature falls too

low, “engage” will be used.

In other words, “energize” refers to the state of the output at the terminal block, and “engage” refers to what the control

algorithm would normally do when controlling a heater under the given conditions.

Installation

All configurations are performed through the Windows application. The CT425 may be powered through USB if desired. This allows the user to configure the unit, or simply become familiar without having to connect separate power. Note: the zerocrossing feature is enabled only if AC power is detected when power is applied.

Mounting

The CT425 may be mounted via case flanges if desired, and may be operated in any position.

Wiring

The terminal block connections are shown in Figure 1. Each group of connections is outlined in the following sections.

Figure 1

TB1:1 – POWER (L/+) TB1:2 – POWER (N/-) TB1:3 – RELAY CONTACT (N.O.) TB1:4 – RELAY CONTACT (N.O.) TB1:5 – SOLID STATE RELAY (-) (AC VERSIONS NON-POLARIZED) TB1:6 – SOLID STATE RELAY (+) (AC VERSIONS NON-POLARIZED)

TB2:1 – RTD INPUT 1 (+) TB2:2 – RTD INPUT 1 (-) TB2:3 – RTD INPUT 2 (+) TB2:4 – RTD INPUT 2 (-) TB2:5 – LOGIC VOLTAGE OUTPUT (+) TB2:6 – LOGIC VOLTAGE OUTPUT (-)

Power

The CT425 is available in AC and DC models. While the external connections appear identical, care must be taken to properly connect the appropriate power supply.

The power input for the AC model is electrically isolated from the rest of the model’s circuitry. The DC model’s power supply is NOT electrically isolated from the rest of the model’s circuitry.

AC Model

On AC models, the line and neutral must be connected to the L/+ and N/- terminals, respectively.

DC Model

On DC models, the positive and negative must be connected to the L/+ and N/- terminals, respectively. The power input has reverse-polarity protection.

Inputs

The CT425 can use any combination of supported sensors which are listed in the table in Sensors. The sensor inputs are not electrically isolated from the rest of the circuitry; therefore care must be taken to not create a

situation where an unintended short circuit is created. Each sensor channel has two terminals. The sensor is simply connected to these two terminals. If the sensor has extra wires

for lead compensation, these wires could be left disconnected or grouped together on the same terminal. Lead compensation may be performed by specifying an offset in the device configuration.

If a shield is provided on a sensor lead, it should be grounded at only one end for best performance. Which end to ground is usually determined through trial and error since otherwise it is extremely difficult to determine. No terminal is provided for grounding since the CT425 does not require grounding. Ground at either the sensor end, or add a separate ground wire at the CT425 end.

Outputs

SSR Output

One SSR output is provided of varying voltage and current ratings depending upon the model. See the table on page 17 for ratings of each model.

The SSR Output is electrically isolated from all other electronics, and will support PID, On/Off, and Alarm functions. The SSR output on AC models will switch AC or DC current, while the DC model will switch current in one direction

only. Note that current will always flow in the reverse direction on the DC model SSR output. This may damage the CT425

when carrying higher current levels due to excessive heat dissipation. Ensure the polarity of the SSR load is correct.

Logic Voltage Output

One Logic Voltage Output (LVO) is provided on the devices. The LVO is not electrically isolated from the rest of the device circuitry; it is intended to drive an external SSR, but could be used for other purposes. The LVO is a currentlimited output and therefore it is not possible to overload this output. However, applying a very low resistance load during power-up will cause the CT425 to enter a special manufacturing mode which is characterized by alternating yellow status indicators. If this happens, simply remove the load and re-apply power. See page 16 for specifications.

The LVO will support PID, On/Off, and Alarm functions.

Relay Output

An SPST relay is provided on the CT425. The Relay Output is electrically isolated from the rest of the device’s circuitry. See the table on page 17 for ratings.

The Relay Output will support On/Off and Alarm functions only. PID is not supported on the Relay Output due to the possibility of the relay being subjected to frequent switching.

USB

All configurations are performed through the USB interface. The included Windows software communicates with the CT425 and allows the user to configure the unit on the fly, or configure, disconnect, and install the device into the intended application. All settings may be stored to non-volatile memory so removal of power does not cause loss of configuration.

The USB interface is not electrically isolated.

Typical Wiring Diagrams

Below are typical wiring diagrams for DC and AC versions of the CT425. Since the SSR and Relay output are isolated, they may use the same power supply that powers the device if desired, or a different power supply.

Figure 2

Figure 3

Configuration

Once the CT425 is attached to a computer and the configuration software is started, press “Connect to Device”. If this is successful, the configuration stored on the CT425 is retrieved and displayed, along with the measured sensor temperature and output status. The settings are grouped into tabs.

Status

The Status group displays each sensor’s current temperature and each output’s state. If the read temperature is outside the range of the device, either “Error Lo” or “Error Hi” is displayed if the sensor resistance is

below or above the input range, respectively. The output status does not take the Reverse Acting setting into account. For example, if the SSR output is at 75% duty cycle,

the output will be energized 75% of the time if Reverse Acting is disabled. If Reverse Acting is enabled, the output will be energized 25% of the time yet the displayed duty cycle will still be 75%.

Figure 4

General Settings

The General Settings group contains the configuration for the RTD inputs, the temperature scale, and device name. Device Name: A string of up to 20 characters that the user may change to “name” the device. This may be useful to identify

multiple units.

Temperature Scale: Determines if the CT425 will interact with the user in the Celsius or Fahrenheit scale. Type: Set to Pt100, Pt1000, Thermistor, or Disabled for platinum 100 ohm, platinum 1000 ohm, thermistors, or no sensor

connected, respectively. See Using Thermistors for more information on thermistor use.

Offset: Applies an offset to the respective sensor input. This could be used for wire lead compensation. Normal Process Value Range: Defines a temperature range that will cause the sensor input’s Status Indicator to be green,

rather than yellow. This provides a quick visual check as to whether the process is within the user’s desired temperature range. See the General Usage on page 13 for more Status Indicator information.

Figure 5

Output Settings

The Output Settings group contains the output configuration. Each output has its own tab within Output Settings. Some options will be unavailable (greyed out) depending upon what function is chosen.

Source: Determines which sensor input the respective output will use. Multiple outputs may share the same sensor input. Function: Disabled, PID, On/Off, or Alarm.

On/Off and Alarm work similarly with the only difference being how Hysteresis is used. Please see the Hysteresis description for further information.

When set to Disabled, the output is de-energized regardless of the Reverse Acting setting. Reverse Acting: Setting this to True causes the respective output to behave in the opposite manner, i.e. normally closed

instead of normally open. This may be useful for cooling applications. Note that when the output is Disabled, the respective output is de-energized regardless of this setting. Also note that despite

setting Reverse Acting to True, the output will not remain “closed” when the CT425 is unpowered. Over/Under: Determines whether the output engages when the sensor temperature is over or under the Setpoint. This applies

to the Alarm Function only. Setpoint: Determines the temperature that the selected sensor input is maintained to for PID and On/Off Functions. In the

case of the Alarm Function, when the sensor is above or below this temperature the output will activate depending upon if Over or Under is selected, respectively.

Hysteresis: Determines the band around the Setpoint where the output engages and disengages. When using the On/Off function, the Hysteresis value is evenly divided around the Setpoint. For example, if the Setpoint is

55.0C and Hysteresis is 0.1C, the output will engage at 49.95C, and disengage at 55.05C. When using the Alarm function, the Hysteresis is placed on the side of the Setpoint that does not engage the output. For

example, if the Setpoint is 55C, Over/Under is Over, and Hysteresis is 0.1C, the output will engage when the sensor exceeds

55.0C, but will disengage when the sensor is less than 54.9C.

+ 16 hidden pages

Minco CT425 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual