Minco CT224 Instructions Manual

CT224

12-Channel Temperature Monitor

Installation and Operating Instructions

Tel: [phone] • Fax: [phone] • www.minco.com

This page left blank intentionally.

Minco Tel: [phone] • Fax: [phone] • www.minco.com 2

Table Of Contents

1. Introduction

2. Pre-Installation

3. Installation

A. Mounting

B. Wiring

1.) Controller Power

2.) Inputs

3.) Outputs

4.) Serial Communications

4. Programming Configuration

A. Using the CT224

1.) Modes / Buttons

B. Entering the Program Settings

C. Setup Worksheet

5. Communications

A. Function Codes

B. Memory Map

6. Specifications

Minco Tel: [phone] • Fax: [phone] • www.minco.com 3

1. Introduction

The CT224 is a universal 12-channel monitor capable of monitoring inputs for any combination of
RTDs, Thermocouples, and 4-20mA loop inputs. The CT224 has 5 outputs, 4 of the outputs can be
used for warning or shutdown signals, the other output is dedicated to signaling alarm conditions.
One internal audible alarm is also present. RS485 or RS232 Serial Communications is also included
on the CT224 and allows use of the Modbus Protocol to communicate data with another device.
MincoSoft CT224 Software is also provided to allow easy communication with the CT224 by using a
computer.

Minco Tel: [phone] • Fax: [phone] • www.minco.com 4

2. Pre-Installation

Figure 1

– Jumper

in position for 4

-

20mA Inputs

The first step before installing the CT224 is to determine the input types that will be used. If analog
4-20mA signals will be used as inputs, jumpers under the rear cover will need to be changed. When
received, the jumpers are set to allow RTD and thermocouple inputs on all input channels. Analog
inputs require that the jumpers be moved to the 4-20mA setting. Follow the simple steps below to
allow 4-20mA loop inputs:

1. Remove the 4 screws that hold the rear cover on. (Do not remove the other 4 screws

that go directly through the board.)

2. Set the rear cover aside.

3. Look at the top of the CT224. There is one jumper for each channel located next to the

corresponding channels terminal block. For all of the channels that will be used for 4­20mA inputs, set the jumper to the position away from the dot. Figure 1 shows a
jumper in the position to allow 4-20mA loops. Leave the jumpers for the other
channels that will be used for RTDs and thermocouples in the dot position. Figure 2
shows a jumper in the position for RTD and Thermocouple inputs.

4. Replace the rear cover and screws.

The CT224 is now ready to accept 4-20mA inputs on the channels that are set like the jumper shown
in Figure 1.

Figure 2 – Jumper in position for RTD or Thermocouple Inputs

Minco Tel: [phone] • Fax: [phone] • www.minco.com 5

3. Installation
A. Mounting

Make a rectangular cut out in the panel where the CT224 will be located. The cutout should
be made according to Figure 3.

Slide the CT224 into the cut out, drill holes for the screws or bolts that will fasten the unit to
the panel. Be sure that the gasket around the CT224 is compressed between the front cover
and the panel so that liquid and debris cannot get behind and inside of the panel.

Figure 3 – Panel Cutout

Minco Tel: [phone] • Fax: [phone] • www.minco.com 6

B. Wiring

The locations of the connections on the CT224 are shown in Figure 4. The rear cover of the
CT224 also shows the connections for each terminal. More detail for each of the connections
is given in the following sections.

Figure 4 – Wiring Connection Locations

Minco Tel: [phone] • Fax: [phone] • www.minco.com 7

1. Controller Power

The CT224 Power connections will vary depending on which type of power is use.

AC

On AC models, the Line and Neutral will be connected to the terminal block in the lower right
hand corner on the rear of the CT224. See Figure 5. The lower terminal on the terminal block
is used for ground. It is important to connect earth ground to the lower terminal if shielded
cable is used for sensors. This connection is how a grounding connection is made to the
shields of the RTDs. Connecting to earth ground also provides a path for current to flow in
the event of an electrical failure and helps to protect the operator from possible electrocution
in such an event.

Fuse

Fuse

Figure 5 – AC Power Connections

Minco Tel: [phone] • Fax: [phone] • www.minco.com 8

DC

On DC models, the DC voltage is connected to the upper terminals and the terminal block in
the lower right corner on the rear of the CT224. See Figure 6. The upper terminal on the
control power terminal block is connected to the positive supply voltage, between 18 and
36Vdc. The lower terminal on the terminal block is used for ground. It is important to
connect earth ground to the lower terminal if shielded cable is used for sensors. This
connection is how a grounding connection is made to the shields of the RTDs. Connecting to
earth ground also provides a path for current to flow in the event of an electrical failure and
helps to protect the operator from possible electrocution in such an event.

Fuse

Fuse

Figure 6 – DC Power Connections

Minco Tel: [phone] • Fax: [phone] • www.minco.com 9

2. Inputs

Maximum Length for

The CT224 can accept any combination of the input types specified in Section 6 at the end of
this document. These may include RTDs, thermocouples, and 4-20mA transmitter loops.
However, some care must be taken when using multiple inputs so that a safe environment is
created for personnel and equipment. For instance, a CT224 should monitor sensors from
only one piece of equipment, especially if high voltage is present. Using this approach,
damage to other devices is greatly reduced, if a circuit fault should occur.

The CT224 does not have channel to channel isolation. This means that grounded
thermocouples cannot be used directly with the CT224. Ungrounded thermocouples may be
used. If grounded thermocouples are used, a device such a Thermocouple Isolator can be
utilized as a means to break ground loops and provide proper inputs to the CT224.

Another consideration due to not having channel to channel isolation is that when using 4­20mA inputs, all loops will share the same return path. Keep this in mind when planning the
system to ensure that it is safe to wire all loops together. It is the system designer’s
responsibility to ensure that good safety measures are used. If unsure about the safety
aspects of a system, call Minco for assistance.

Each input channel has 3 input terminals and a common earth ground terminal. The
terminals are labeled as A, B, C and D. Terminal D is connected to earth ground, when earth
ground is connected to the terminal block as described in Section 1, Controller Power. Input
wiring for the different input types is shown in Figures 7, 8, 9, and 10.

RTDs - RTDs Use three terminals per channel. Care should be taken to not exceed 30 ohms of
lead wire resistance. Chart 1 shows maximum lead wire length per lead of an RTD so as not to
exceed the 30 ohms maximum lead wire resistance. Leadwire for RTDs should be twisted and
shielded, this will reduce fluctuations in the readings due to noise.

3-wire RTD: The odd colored wire must be connected to terminal A of the input channel.
The other two wires can be placed in either order in B and C. If the RTD has a shield, place it
into terminal D. When adding leadwire to the RTD, be sure to use the same length and gauge
for each lead. The CT224 is able to provide very good compensation for leadwire resistance
as long as each lead has the same resistance. Recommended Extension Leadwire: Belden
1031A or any other wire that is twisted and shielded is a good choice.

Leadwire

(AWG)

Ohms/Foot at

25ºC

18 .0065 4615
20 .0103 2912
22 .0165 1818
24 .0262 1145
26 .0418 717
28 .0666 450

30 ohms of

Resistance

Chart 1 – Leadwire Resistance per lead

Minco Tel: [phone] • Fax: [phone] • www.minco.com 10

Figure 7

– 3-

Wire RTD Wiring

2-wire RTD: One of the leads should be placed in terminal A for the input channel. The
other lead should be placed in either B or C. A jumper wire must be placed between B and C
in order to complete the input circuit. If the RTD has a shield, connect it to terminal D.
Recommended Extension Leadwire: Belden 1030A or any other wire that is twisted and
shielded is a good choice.

The 2-wire RTD will exhibit some error due to the inability to compensate for lead wire
resistance. This can be partially compensated by using the Zone Offset feature as shown later
in the manual under the Programming Configuration section. Chart 2 shows lead wire
resistance based on wire gauge. The desired offset value can be calculated using the chart,
length of leadwire, and by visiting www.minco.com and using the “Sensor Calc” program to
determine the affect of the leadwire. By using this information it is possible to reduce the
leadwire error by adjusting the offset.

Figure 8 – 2-Wire RTD Wiring

Minco Tel: [phone] • Fax: [phone] • www.minco.com 11

Thermocouples – Thermocouples use terminals B and C. The positive lead on the
thermocouple should be connected to the B terminal and the negative lead to the C terminal.
On a thermocouple the red lead is usually negative (–) and the other lead is usually positive
(+). Figure 9 shows how to wire the Thermocouple to the CT224.

Figure 9 – Thermocouple Wiring

4-20mA – 4-20mA inputs use terminals B and C. The loop positive should be connected to

the B terminal and the loop negative should be connected the C terminal. When configuring
the CT224 for 4-20mA loops, you must set the jumpers located on the top part of the PCB to
the position with out the dot. This is shown in Figure 1 in the Pre-Installation Instruction
section.

Figure 10

– 4-20mA Wiring Diagram

Minco Tel: [phone] • Fax: [phone] • www.minco.com 12

3. Outputs

Two types of outputs are available on the CT224, relays or logic. The output type is
determined by the options that were ordered.

There are three terminals for each output. All three terminals are used when relays are the
output type. When logic outputs are installed, only two of the terminals are used. The
terminals are labeled as A, B, C. Caution: The terminal positions are A, B, C on the left side of
the unit reading from top to bottom, but they are labeled as C, B, A on the right side of the
unit.

The CT224 has 5 outputs. Four of the outputs are used for signals and can be configured to
trip and untrip in several different ways. The different methods are covered in section

4. Program Configuration part B) Entering The Program Settings. The Alarm Output
differs from the other 4 outputs in several ways. The Alarm Output will use the hysteresis
value for the channel that caused it to trip as it’s untrip value. If the alarm is configured to
sound with a channel that is set to latch another output on a trip, the alarm will continue to
sound until a key is pressed. The Alarm Output cannot be configured for reverse acting, it is
always direct acting.

Relay outputs: Relays are SPDT, they have terminals for both normally open (NO) and
normally closed (NC) contacts. The NO contact is between terminals B and C and the NC
contacts are between terminals A and B.

Logic outputs: Logic outputs use terminals A and B, with B as the reference ground. Logic
outputs are not isolated from the controller supply. Caution must be taken when using logic
outputs since several devices may be sharing the same reference ground when they are
connected.

Minco Tel: [phone] • Fax: [phone] • www.minco.com 13

4. Serial Communications

Modbus protocol is used to communicate between the CT224 and other device (PC or PLC).
Two physical interface options are available for serial communications. They are RS232 and
RS485. The CT224 is always a slave device.

RS485

RS485 allows for multiple devices to be connected to one network. Up to 128 CT224 can be
connected to a network. The RS485 standard allows up to 32 nodes to be connected on a
half-duplex network. However, each CT224 accounts for only ¼ of a node, so 128 CT224 can
be connected to the network when RS485 is used as the medium.

The connections on the CT224 are labeled as A, B, and S. The two signal wires are A and B.
The A terminal should be connected to the A terminal on the RS232 to RS485 converter. The
B terminal should be connected to the B terminal on the RS232 to RS485 converter. The S
terminal should be connected to the shield. The shield wire should be connected to ground
in one location only, to avoid ground loops, which can cause erratic communications. Refer
to Figure 11 for a wiring diagram.

RS232

Terminal A is the Transmit Data (TD) connection, terminal B is the Receive Data (RD)
connection, and terminal S is the Signal Ground (SG) connection on the CT224. RS232 devices
require Terminal A connected to Receive Data from the master device, Terminal B to Transmit
Data from the master device, and terminal S to Signal Ground. For a 9-pin D-Sub connector
on a PC, connect A to pin2, B to pin 3, and S to pin 5. Caution should be taken when using
RS232, as it is not isolated. This could cause ground loops through devices, which could
cause damage to the CT224 and / or other devices. Refer to Figure 11 for a wiring diagram.

Minco Tel: [phone] • Fax: [phone] • www.minco.com 14

RS485

RS232

Figure 11

– Wiring diagrams for RS232 and RS485

Minco Tel: [phone] • Fax: [phone] • www.minco.com 15

Connecting Multiple CT224

A network of CT224’s should be wired so that the CT224’s are in a chain. However, only
devices using RS485 can be connected in this manner. RS232 will only allow one (1) device to
be connected to a port, so RS232 devices cannot be used in a network. A star or ring
configuration is not appropriate for RS485. Each CT224 should only be connected to at most
2 other CT224. Figure 12 shows the basic wiring for a chain configuration. Like terminals on
the CT224’s should be connected together in the chain, A to A, B to B, S to S.

Figure 12 – Master Slave Chain

End devices (Master and last Slave) on an RS485 network should be terminated to achieve
error-free communications. The termination should match the characteristic impedance of
the network. Normally this value is about 120ohms. Figure 13 shows how to easily apply a
termination resistor to the last CT224 in a chain. Do not use more than 2 termination resistors
on the network. There are many other methods for terminating an RS485 network. If
interested in trying a different termination approach, consult the Internet for various other
configurations. In most applications, terminating with 120ohm resistors will provide error­free communications.

Figure 13 – Termination of RS485 Network

Minco Tel: [phone] • Fax: [phone] • www.minco.com 16