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OMRON PLC Beginner Guide

In general a Control System is a collection of electronic devices and equipment which are in place to ensure the stability, accuracy and smooth transition of process or a manufacturing activity. It takes any form and varies from power plant to a semi-conductor machine. As a result of rapid advancement of technology, complicated control tasks accomplished with a highly automated control system, which may be in the form of Programmable Logic Controller (PLC) & possibily a host computer, etc. Besides signal interfacing to the field devices ( such as operator panel, motors, sensors, switches, solenoid valve and etc.), capabilities in network communication enable a big scale implementation and process co-ordination besides providing greater flexibility in realizing distributed control system. Every single component in a control system plays an importnat role regardless of size. For instance, as shown in Fig 1.1. the PLC would not know the happenings around it without any sensing devices. And if necessary, an area host computer has to be in place to co-ordinate the activities in a specific area at the shopfloor.

MELSECQ PLC Modbus Master Guide

Melsec Q Series PLC Modbus Master program makes it possible that Mitsubishi QnA, QnAS and Q series PLC can act as a Modbus master to communicate with Modbus slave device in RTU mode.

In order to be the master, a communication module “QJ71C24” or “QJ71C24-R2” is needed when the PLC is Q series, while module “A1SJ71QC24N”, “A1SJ71QC24” , “AJ71QC24N” or “A1SJ71QC24-R2”, etc., is needed.

Automating Control Systems with PLCs

Control systems apply artificial means to change the behavior of a system. The type of control problem often determines the type of control system that can be used. Each controller will be designed to meet a specific objective. The major types of control are shown in Figure 1.1.

Figure 1.1 Control Dichotomy

S7-200 Tips : Modem Network

Special Hardware Requirements:

One (1) SIMATIC S7-200 CPU
One (1) Programming device or PC
Two (2) Bausch Induline modems:
One (1) DTU-3000
Three (3) Interface cables

PC/programming device/modem connection
Modem/DTU-3000 connection
DTU-3000/PPI network connection

This example shows how an S7-200 multiple master PPI network can be accessed by a PC or programming device over a PC/PPI cable by means of a modem connection and the DTU-3000 by PanelTec. (A network with up to three masters was tested.) This allows the user to program or monitor a remote PLC with MicroWin. The modem used must support a character string of 11 bits for communication.

DTU – 3000: Description and Technical Specifications

Communications:
300 baud to 19.2 kbaud
3 serial communication ports DB-25
RS-232, RS-422, RS-485

Power Requirements:
9V to 28V
3 W

S7-200 Tips : Micro/Win Modem Support

Note! In the latest STEP 7-Micro/WIN Version 3.2 (or greater) the Modem handling has been revised.
As a result, this tip only applies to projects using Micro/Win versions prior to version 3.2

Special Hardware and Software Requirements:

One SIMATIC S7-200 (CPU 212 or higher)
One Siemens 5-switch PC/PPI cable (preferred). Order number 6ES7 901-3BF200-0XA0
One Siemens 4-switch PC/PPI cable (optional) and a null modem adapter
One RS-232 cable (9-pin female/25-pin male) to connect the PG/PC to the local modem. Some modems require a 9-pin female/9-pin male connector; check your local modem connection.
One set of European or U.S. modems with 9.6 kbaud or 19.2 kbaud support
One STEP 7-Micro/WIN 32 version 3.x software package

This application tip gives a summary of modem support for STEP 7-Micro/WN 32 version 3.x. All predefined modems have been tested and verified using the European CTA 104 C T-Net phone line simulator and the U.S. Ring-It phone line simulator. Modem tests consisted of 10-bit or 11-bit data formats at the rates of 9.6 kbaud and 19.2 kbaud, using the isolated 5 switch PC/PPI cable. The 5-switch cable eliminates the need for a null modem adapter between the PC/PPI cable and the remote modem. Use of a 4-switch PC/PPI cable requires a null modem adapter and the 11-bit data format strings.