The Tracker 240 series of digital panel meters are specifically for use with load cell transducers and as a panel meter for weighing applications. All the Tracker 240 panel meters have a 5-digit display and transducer supply plus many software features including tare, offset zeroing, in-flight compensation, peak picking and extensive alarm functions.

As standard, the Tracker 240 has an analogue output and an RS422/485 2 or 4-wire communications interface.

The Tracker 244 has 2 relay outputs to control external devices and the Tracker 245 has 4 TTL logic outputs. The displayed value can be in tonnes, litres, grams or any other engineering unit. You can use the Tracker 240 panel meter series in conjunction with up to 4 x 350 Ohm load cells; this uses a 6-wire ratiometric measurement technique.

Transducer Excitation Supplies

10V DC (or 20 volt DC for use with I.S. barriers) fully drift compensated.

6-Wire Ratiometric Input

Sensor Connections

The Tracker 240 digital panel meters use a 6-wire ratiometric method of measurement. It is possible to connect up to 4 x 300 Ohm load cells in parallel. More can be used if the resistance is higher (e.g. 8 x 700 Ohm load cells) and the total current does not exceed 120mA at 10V DC. An external 10V DC supply can be used, if required, still retaining the ratiometric measurement capability.

Analogue Output

The user programmable analogue output allows the Tracker 240 panel meters to transmit the measured display value, the maximum, minimum or average value, or a value sent via the serial interface. The analogue output can be scaled for any portion of the display range and is configurable for 4-20mA, 0-20mA or 0-10 volt signals. Electrical isolation ensures that you avoid problems associated with earth loops.

Calibration Scaling and User Linearisation

Calibrating the Tracker 240 panel meters to load cells can be achieved in one of two ways. You can enter the values from the strain gauge manually or the Tracker 240 can read the actual output from the transducer at 2 points in the range, normally at zero and another point near the maximum load that you want to measure. These measured values are stored with their associated display values as the calibration parameters. For more demanding applications, you can independently calibrate the Tracker 240 panel meter (up to 8 points) to compensate for any non-linearity from the load cell.

Display

The user can configure the Tracker 240 digital panel meter for the required engineering units and display resolution. The resolution is user configurable for 1, 2, 5 and 10 digits. This can be useful if a steady reading is difficult to achieve. Normally the full resolution would be displayed. For noisy signals, we canprovides an independent display filter. You can select the display update rate to be 2, 4 or 10 per second, and adjust the brightness to suit ambient lighting conditions.

Smart Filter

Often plant vibration can affect the measured values and make the display appear "noisy". The Tracker 240 panel meter has a smart filter that samples the "noisy" signal from the load cells and then calculates a filter band value. When in use, the panel meter only applies the filter when the measured value rate of change is within the filter band. To allow a fast response for real change of signal, the panel meter turns the filter off until the signal rate of change is again within the filter band limits.

Digital Status (Logic) Inputs

Data Track supply the Tracker 240 digital panel meters with two logic inputs to allow remote control of the panel meter functions via external devices such as switches or PLCs. Volt free contacts or open collector TTL outputs may activate the inputs. You can individually program the 2 inputs to perform one or more of the following functions:

Tare, Zero, Part Count, Display Hold, Display Maximum (Peak), Display Minimum (Valley), Display Average, Display Reset (Peak Picking Mode), Display Test (Lights all Display Segments), Keyboard Lock, Alarm (Latch) Reset, Alarm Disable, Analogue Output Hold,

You can use the 5 front panel buttons to set up a panel meter by stepping through a simple password protected menu. In addition, you can individually program the 2 front panel function buttons to give operator level access to one or more of the following functions:

Alarm Menus

Alarms can be flashed on the panel meter display along with the measured value. You can individually configure the following parameters for each of the 4 alarm menus:

• High, Low or Deviation Alarm Action
• High and Low Band Limits (Deviation Action only)
• On and Off Delay Timers
• On and Off Hysteresis
• Latching or Non-Latching
• Normal or Pulsed Output Modes
• Setpoint Adjustment (during normal running or only via password protected menus)
• When Filling Modes are selected, Digital (TTL/ Relay) Outputs 1 and 2 are automatically assigned

Serial Communications

The Tracker 240 digital panel meters are equipped with an isolated RS422/485 serial communications interface to allow connection to computers or PLCs. Data Track supply three protocols as standard to allow easy integration with most SCADA packages. You can also select Master Mode to allow digital transmission to a remote repeater display or printer. Consult your supplier if you require RS232 instead of RS422/485. The combination of a Tracker 240 panel meter and an HMI, fitted with a Modbus compatible RS485 interface, becomes a powerful stand-alone batch control and recipe selection system. You are able to tailor the HMI's display and function buttons for any application and language. Many HMI units can also be a gateway for Fieldbus connection (e.g. Profibus, Device Net). A single HMI can communicate with up to 32 Tracker 240 panel meters.

Universal Power Input

Wide-ranging 90-265V AC input allows world-wide installation. A low voltage 24V AC/DC input option is available.