Modbus Rtu; Discrete I/O; Plc Interfaces; Analog Output - Mettler Toledo IND131 Guia De Instalacion

continuous output, SICS host communications, Modbus RTU and ASCII command input (C, T, P,
Z).
1.10.1.1.

Modbus RTU

Modbus RTU is a serial communications protocol published by Modicon in 1979 for use with its
programmable logic controllers (PLCs). It is a standard serial communications protocol in industry.
The RTU format follows the commands/data with a cyclic redundancy check checksum as an error
check mechanism to ensure the reliability of data. Modbus RTU is the most common
implementation available for Modbus. Most Modbus devices communicate over a serial EIA-485
physical layer but RS-232 is also supported.
1.10.2.

Discrete I/O

The discrete I/O interface option is available with dry-contact or solid state relay outputs. The relay
contacts will switch up to 30 volts DC or 250 volts AC at 1A. The solid state outputs will switch up
to 30 volts DC at 350mA maximum.
The inputs are switch selectable as either active (for simple pushbutton control) or passive (for
connection to PLCs or other devices that supply their own power for the inputs).
1.10.3.

PLC Interfaces

IND131 and IND331 interface options include 4-20mA Analog Output, A-B RIO, CC-Link,
ControlNet, DeviceNet, Ethernet/IP, Modbus TCP and PROFIBUS DP. Additional details about each of
these interfaces can be found in the IND131/IND331 PLC Interface Manual, provided on the
documentation CD.
1.10.3.1.

Analog Output

The Analog Output option provides a 4-20mA analog signal corresponding to the gross or net
weight or the rate The analog signal is isolated and requires that the connected device have a
maximum internal resistance of 500 ohms.
Two solid state error outputs are provided to indicate out of range and error conditions.
1.10.3.2.

A-B RIO

The A-B RIO option enables data exchange by bi-directional communications using the Discrete
Data Transfer mode. The IND131/IND331 terminals provide new information for the PLC
approximately 20 times per second. This communication is a high-speed, real-time message
interface between the terminal and the PLC for process control. Division, integer, and floating point
values are supported. The A-B RIO interface does not support Block Transfer mode.
1-12 METTLER TOLEDO IND131/IND131x/IND331/IND331xx Installation Manual
THE INTERNAL DISCRETE I/O RELAY OPTION (#72225753 OR #72225757) MUST NOT BE USED
IN A TERMINAL INSTALLED IN AN AREA CLASSIFIED AS DIVISION 2 OR ZONE 2/22. FAILURE TO
COMPLY WITH THIS WARNING COULD RESULT IN BODILY HARM AND/OR PROPERTY DAMAGE.
WARNING
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