Specifications
18
Application operating modes are the most structuring elements in the automatism system denition phase.
They determine the denition of the hardware and software part of an application and they act on all architecture
components: SCADA, PLC, and motor control device wiring.
Operating modes, described below, are rather general and can be easily adapted to the specic constraints of a
project.
The objective is to propose operating modes which allow starter management in remote mode with PLC or in
local mode with buttons or panel.
Remote mode b
In Remote Mode the motor can be controlled either by the PLC (Auto Mode) or by the SCADA/HMI operator
(Manual Mode).
When both SCADA and local HMI are able to control Auto or Manual modes, the rst station turning to Manual
mode has the lead to manually control the actuator and to come back to Auto mode.
In Manual mode any motor can be controlled remotely from a Human Machine Interface. This operating mode can
be considered risky in some targeted applications; therefore, this proposed solution can be modied to meet this
constraint.
Local mode b
In Local mode, an operation can be performed on actuators even in the event of a PLC fault. That means that local
controls are hardwired directly to the pre-actuator (ie, to contactor or variable speed drive hardwire control
circuits).
Motors can be controlled with local buttons or for variable speed drive VSD ATV61 using a Local interface.
It is possible to switch the actuator to Off mode, for maintenance purposes, in order to inform the PLC application.
For maintenance actions this mode requires an additional electrical padlocking.
When switching from Auto to Manual mode using SCADA/HMI, actuators keep its state (that means go on running
if it was running previously, and keep the same speed for motors controlled by variable speed drives)
The power can be switched off by a switch. For all these modes, the emergency button is active.
Principle
Introduction
3-Application design
Operating modes
The aim of this chapter is to provide recommendations that facilitate the design phase of your process control
project.
It comprises three main parts:
Description of global application operating modes -
Description of hardware design -
Description of software design -