Applications

Temperature Control & Display

Tracker 200 series panel meters for applications requiring temperature display.

Industrial Temperature measurements are usually using Thermocouples, RTD or other Resistance sensors. Some applications a 2-wire transmitter may be used, particularly if distances between the sensor and the instrumentation are large.

The following instruments can measure thermocouples and RTD directly or power and measure 2-wire transmitters.

• Tracker 211 Low Cost 4-Digit Indicator
• Tracker 212 Low Cost 5-Digit with 4-20mA signal linearisation
• Tracker 220 Series - High accuracy 4/5-Digit + RS485

All the products listed above have the following as standard or can be fitted as an option:

• Isolated Analogue Output
• Alarm Relays
• Max / Min Memory + Reset
• User Calibration Function (see below)

Using the user calibration feature, the Tracker and sensor can be match calibrated together where the instrument measures and stores the sensors signal at two known temperatures. This greatly reduces errors due to sensor output variations. The displayed values can be in °C or °F (and Kelvin on the 220 and 300 series).

All Tracker temperature measuring instruments have an automatic Cold Junction Compensation (CJC). On the Tracker 220 series the user can also select an external reference junction temperature and select up- or down-scale sensor break detection.

In applications where non-linearising temperature transmitters are used, the Tracker 220 series can linearise a 4-20 mA signal to the required thermocouple curve.

Checks are also made for partial electrical load failure or other heater problems such as SSR faults, shorts and open circuits.

Pressure & Weighing

A variety of pressure transducers, pressure transmitters or strain gauge bridges can be connected to a Tracker 211, 220, or 240 series.

Pressure and weighing sensors are generally supplied as a 350Ω strain gauge bridge device, requiring a regulated excitation supply and outputting a millivolt signal, or a 2-wire transmitter which requires a 24VDC supply and outputs a 4-20mA signal.

The following instruments can power and measure both these sensor types:

• Tracker 210 Low Cost 4-Digit Indicator
• Tracker 212 Low Cost 5-Digit with 4-20mA signal linearisation
• Tracker 220 Series - High accuracy 4/5-Digit + RS485

For multiple load cells (multiple strain gauge bridges):

• Tracker 240 5-Digit Load Cell Indicator + RS485

All the products listed above have the following as standard or can be fitted as an option:

• Isolated Analogue Output
• Alarm Relays
• Zero Function
• Tare Function
• Max / Min Memory + Reset
• User Calibration Function (see below)

Using the user calibration feature, the Tracker and sensor can be match calibrated together where the instrument measures and stores the sensors signal at two or more pressures or weights. This greatly reduces errors due to sensor output and excitation supply voltage variations. The displayed values can be in any engineering units.

On the 200 series a front panel button, or status (logic) inputs on some models, can be configured to provide an auto zero feature allowing zero offset errors to be eliminated. For weighing applications, a tare function can be similarly configured.

Process Inputs

The Tracker 200 digital panel meters for the measurement of process signals.

Industrial signals are loosely associated as process are 0-5VDC, 0-10VDC, millivolts DC and the most popular 20mA loops (e.g. 4-20mA). These are scaled as a range in engineering units e.g. 0-10VDC = 0-500 Litres Per Hour.

The Tracker Instruments that can accept ±20mA, ±10VDC and ±100mV are:

• Tracker 211 4-Digit Low Cost
• Tracker 212 5-Digit Low Cost with 4-20mA Linearisation
• Tracker 220 Series 4/5-Digit High Accuracy + RS485

All of the above have as standard or can be fitted as an option:

• 10V and 24VDC sensor / loop excitation supplies (Standard all models)
• Isolated Analogue output
• Alarm Relays
• Zero Function
• Tare Function
• Max/Min and reset

All the instruments listed above can also connect directly to thermocouples and RTD temperature sensors making their inputs "Universal".

Signal Re-Transmission

Isolated analogue outputs.

Analogue outputs are used to isolate and transmit a value in form of a analogue signal. For example to transmit a temperature measured by a Type K Thermocouple as 4-20mA = 0-500°C

The following Instruments have analogue outputs or options:

• Tracker 211 4-Digit Low Cost - Optional 4-20mA output
• Tracker 212 5-Digit Low Cost - Optional 4-20mA output
• Tracker 223 & 224 5-Digit High accuracy - 0/4-20mA / 0-10VDC (Fitted as standard)
• Tracker 240 5-Digit Load Cell Indicator - 0/4-20mA / 0-10VDC (Fitted as standard)
• Tracker 260 5-Digit LVDT Indicator - 0/4-20mA / 0-10VDC (Fitted as standard)
• Tracker 280 5-Digit Counter/Timer Indicator - 0/4-20mA / 0-10VDC (Fitted as standard)

The output can be configured to transmit the measured value or the averaged, maximum or minimum value. It has its own damping filter for noisy or fast moving signals. The input can be locally conditioned and re-transmitted over a long distance. Being electrically isolated, problems associated with earth loops causing noisy and inaccurate measurements are eliminated.

If 4-20mA outputs are configured then the analogue output signal will not fall below 4mA or exceed 20mA.

Remote Data Acquisition

Tracker Instruments are Modbus RTU compatible for compatibility with most data acquisition software.

The RS485 serial interface on Tracker instruments are electrically isolated and have four protocols including the widely used Modbus RTU. This allows a centralised "Master" device (e.g. a PC) running a data acquisition program to pole "slave" devices to receive real time data. This data can be viewed graphically in real time, archived for review later and give alarm alert if the values are outside preset limits.

Some system also allow values to be sent from the Master to the slaves, e.g. Set-point values.

Demonstration data acquisition software can be downloaded here.

The following instruments have a RS485 interface fitted as standard:

• Tracker 211 4-Digit Low Cost - Optional 4-20mA output
• Tracker 220 Series 4/5-Digit High accuracy Process inputs
• Tracker 240 Series 4/5-Digit Load Cell Indicators
• Tracker 260 Series 5-Digit LVDT Indicators
• Tracker 280 Series 5-Digit Timer/Counter/Frequency Indicators

You can connect up to 32 devices to a single master device in a multi-drop configuration. You can control the display and analogue output via the serial interface, allowing any device to be used as a remote display or control device.

Alarm Outputs

Comprehensive alarm functions are built into the Tracker Instruments.

All Tracker instruments have alarm output options with volt free relay contacts and TTL outputs on some models. On the panel meters an alarm state message can be flashed on the display along with the measured value.

The following instruments have alarm outputs and options:

• Tracker 211 4-Digit Low Cost - Optional 4-20mA output
• Tracker 211 4-Digit Low Cost, 1 C/O as standard, optional +1 C/O +1 N/O
• Tracker 222 4-Digit High Accuracy, 2 C/O as standard
• Tracker 224 5-Digit High Accuracy, 2 C/O as standard
• Tracker 244 5-Digit Load Cell Indicator, 2 C/O as Standard
• Tracker 245 5-Digit Load Cell Indicator, 4 TTL outputs as standard
• Tracker 264 5-Digit LVDT Indicator, 2 C/O as standard
• Tracker 265 5-Digit LVDT Indicator, 4 TTL Outputs as standard
• Tracker 284 5 Digit Timer / Counter, 2 C/O as standard
• Tracker 285 5-Digit Timer / Counter, 2 TTL outputs as standard

C/O = Volt free Change Over contacts, N/O = Volt free Normaly Open contacts.

On the Tracker 211 low cost series the following alarm parameters are available:

• Alarm Type - None, High, Low
• Alarm message display - On Off (For all alarms)
• Setpoint (max 3 alarms)
• Hysteresis

All other instruments (per alarm):

• Alarm Type - None, High, low, Deviation (band)
• Setpoint (max 4 alarms)
• Deviation High
• Deviation Low
• Latching - On Off
• Output selection (Which outputs switch if any)
• On Delay (Seconds)
• Off Delay (Seconds)
• On Hysteresis
• Off Hysteresis
• Edit Setpoint - On Off (Operator access at run time)
• Alarm Message display - On Off
• Relays energised or de-energised in the alarm state

The hysteresis facility stops noisy signals switching outputs rapidly (relay chatter).

High and low deviation creates a band around the set-point value. The alarm will be activated if the measured value is out of this band.

On and off delay times can be set to stop fleeting alarms. The measured value must be continuously in the alarm condition for the time set before the alarm becomes activated.

Individual alarms configured as latching or non-latching. Latched alarm require to be acknowledged by the front panel push buttons or, on models fitted with status inputs, via remote volt free contacts.

Fill & Trickle Feeder Control

The Tracker 240 digital panel meter has relay or TTL outputs for batch filling applications.

Filling sequence

The Tracker 244 and 225 have 2 relays with volt free contact or 4 TTL outputs respectively. These outputs can be used for alarms or for a batch control filling sequence.

The filling modes can be "Fill", where the container to be filled is on the load cells, or "Loss of weight" where the product's reservoir/tank is on the load cells.

Typical Fill Control Sequence

This sequence will detect a new empty container is in position and will fill to 97Kg (Setpoint 1 / Output 1) and then trickle feed to 100Kg (Setpoint 2 / Output 2) to avoid over filling.

• 1. Start Trigger - detects the weight of a empty container (Optionally triggered by a logic input or front panel push button)
• 2. Wait Predetermined time (seconds)
• 3. Tare Load cell value
• 4. Zero and start cut-off Timer (Pre-set maximum fill time) *
• 5. Switch Outputs 1 and 2 on (Fill and Trickle feed valves open)
• 6. Wait until 97Kg is measured or cut-off timer pre set time exceeded *
• 7. Turn Off Output 1 and 2
• 8. Wait Pre set in-flight time
• 9. Store actual weight (e.g. 97.35Kg) **
• 10. Turn on output 2 (trickle feed valve open only)
• 11. Wait until 100Kg delivered or cut-off timer exceeded *
• 12. Turn off Output 2
• 13. Wait in-flight time
• 14. Store weight value (e.g. 100.12Kg) **

* The sequence will be terminated immediately if the cut-off time is exceeded.
** The actual fill weights are stored to calculate the in-flight set-point adjustments for the next sequence to improve filling accuracy.

Timer / Counter

The multitude of functions on a Tracker 280 make it ideal for this role.

Applications for the Tracker 280 digital panel meter include:

• Pulse Totalisation - Pulses scaled to engineering units
• Pulse Rate - Scaled pulses for rate (e.g. Litres per minute)
• Frequency Measurement - Scalable to engineering units (e.g. rpm)
• Up/Down Counting (Uses both channels)
• Batch control
• Position Measurement with encoders (Uses both channels)
• Encoder quadrature measurement (Uses both channels)
• Timing

Maths functions include:

• Tare, zero, pre-set, Max /Min
• Channel 1 + Channel 2, Channel 1 - Channel 2
• Elapsed time, Total Time, Average Time
• Period cycle time, Ratio of a period, Ratio channel 1 v Channel 2