Mettler Toledo LJ16 Spécifications télécharger pdf (Page 115)

METTLER TOLEDO Weigh Module Systems Handbook

(12/99)13-2

than discrete outputs but have a slower update rate. Long cabling distances are

possible, but connection with a PLC requires additional hardware/software.

These outputs can communicate in demand, continuous, or host mode. Demand mode

sends weight data to a printer or other device only when requested. Continuous mode

transmits weight data repeatedly to a remote display or other device. Host mode allows

two-way communication between the scale and a host computer.

Direct PLC Interface

A direct PLC interface makes it possible to transmit the following types of information:

• Weight Data: gross, tare, net, rate.

• Status Data: motion, net mode, setpoints, data integrity.

• Commands: tare, clear, print, zero, load setpoint, load tare, control display

messages.

• Floating Point Data: special format with additional data and commands.

It requires a special printed circuit board (PCB) to interface with a specific

manufacturer’s PLC. The following options are available for METTLER TOLEDO Jaguar

and Panther indicators:

• Allen-Bradley™ RIO – This PCB enables an indicator to operate as an Allen-Bradley

remote input/output (RIO) device. It allows discrete transfer of data from the

indicator to the PLC and block transfer of data between the PLC and other devices.

• Profibus™-DP – This PCB enables an indicator to communicate with a Siemens or

Texas Instruments PLC. Discrete data can be input or output in large blocks.

• Modbus Plus™ – This PCB enables an indicator to communicate with a Modicon

PLC. Discrete data can be input or output in large blocks.

Weighing Accuracy

Dynamic Weighing

Vibration or motion on a scale can make it difficult to get an accurate weight reading.

For dynamic weighing applications where the load on a scale is constantly in motion,

indicators need to be able to take a series of weight readings and use those readings to

calculate an average weight.

Filtering

Environmental noise is vibration caused by nearby machinery, unstable structures, or

wind and air currents. Instead of calculating an average weight reading, most indicators

can filter out this noise. An indicator with a wide range of filtering levels usually can

provide the best combination of noise reduction and update speed.

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Mettler Toledo LJ16 Spécifications Page 115