Black Box IC108A Guia do Utilizador descarregar pdf (Página 52)

Advant

Smart Device (HART

) Interface User’s Guide

Chapter 2 Installation

2-40 3BUR 001 085R0001 REV A

ROC Read Output Coil

RIR Read Input Register

ROR Read Output Register

SCAC Scan Complete Acknowledge to a Coil

SCAR Scan Complete Acknowledge to a Register

Performing Reads and Writes for smart devices

Smart devices use the following definitions:

Coil is a discrete device. Discrete outputs are called output coils and inputs are

called input coils, input statuses, or discrete inputs.

called output or holding registers.

ModbusB memory locations are listed in Table 2-15.

The interface software automatically performs Modbus read/write commands to the appropriate

SHIM memory locations. Based on Smart transmitter information in the configuration templets.

Reading Coils and Registers

Four commands are used to read the memory locations:

RIC Read Input Coil

ROC Read Output Coil

RIR Read Input Register

ROR Read Output Register

Scan Acknowledge Commands

The scan acknowledge commands, SCAC and SCAR, are executed only after a read is

completed and provide a means to inform the smart device that all its data has been read by

writing a “1” value to either the coil or register specified. When a smart device detects the scan

Table 2-15. ModbusB Memory Locations

ModbusB Data Type

MOD 300 Range in

PLC Command Templet

Output Coil 1-9999

Input Coil 10001-19999

Input Register 30001-39999

Output Register 40001-49999

1 2 ... 47 48 49 50 51 52 53 54 55 56 57 ... 117 118

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Black Box IC108A Guia do Utilizador Página 52