vb.net barcode reader Interfacing Outputs in Software

Make Data Matrix ECC200 in Software Interfacing Outputs

Interfacing Outputs
Data Matrix 2d Barcode Recognizer In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Data Matrix Encoder In None
Using Barcode generator for Software Control to generate, create Data Matrix image in Software applications.
As mentioned previously, most output circuits require more voltage and current than the control electronics (computer, microprocessor, microcontroller) of your robot can provide. Therefore, you need some type of power driver to convert the 0 5 volt (off/on) signals provided by the control circuitry into the current and/or voltage levels required by the output. Figs. 29.2 through 29.7 show various approaches for doing this, including relay, transistor, power MOSFET, discrete component H-bridge, single-package H-bridge, and buffer circuits. All have their advantages and disadvantages, and they are described in context throughout this book. See especially 18, Working with DC Motors, and 19, Working with Stepper Motors, for more information on these power drive techniques.
Recognize Data Matrix 2d Barcode In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Making ECC200 In Visual C#.NET
Using Barcode creation for VS .NET Control to generate, create Data Matrix image in VS .NET applications.
Relay contacts V+ or signal
Data Matrix ECC200 Generation In Visual Studio .NET
Using Barcode encoder for ASP.NET Control to generate, create Data Matrix 2d barcode image in ASP.NET applications.
Data Matrix ECC200 Maker In .NET Framework
Using Barcode encoder for .NET Control to generate, create Data Matrix ECC200 image in Visual Studio .NET applications.
1N4001
Making Data Matrix ECC200 In VB.NET
Using Barcode creation for Visual Studio .NET Control to generate, create Data Matrix image in .NET applications.
Generate USS-128 In None
Using Barcode generation for Software Control to generate, create GTIN - 128 image in Software applications.
Relay
Code 128 Code Set A Creation In None
Using Barcode printer for Software Control to generate, create Code128 image in Software applications.
Barcode Encoder In None
Using Barcode maker for Software Control to generate, create bar code image in Software applications.
FIGURE 29.2 Relay interface.
ANSI/AIM Code 39 Creator In None
Using Barcode generator for Software Control to generate, create Code-39 image in Software applications.
EAN-13 Supplement 5 Generator In None
Using Barcode printer for Software Control to generate, create EAN 13 image in Software applications.
440 INTERFACING WITH COMPUTERS AND MICROCONTROLLERS
Making 2/5 Standard In None
Using Barcode encoder for Software Control to generate, create C 2 of 5 image in Software applications.
Paint Barcode In None
Using Barcode maker for Microsoft Excel Control to generate, create bar code image in Office Excel applications.
10K 1K Input b e c Output
ECC200 Generator In C#.NET
Using Barcode creator for Visual Studio .NET Control to generate, create Data Matrix ECC200 image in Visual Studio .NET applications.
Bar Code Recognizer In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
1K Input b
Drawing GTIN - 12 In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create UPCA image in ASP.NET applications.
Bar Code Creation In .NET
Using Barcode drawer for Reporting Service Control to generate, create bar code image in Reporting Service applications.
e Output 10K
USS Code 128 Creator In None
Using Barcode maker for Online Control to generate, create Code 128C image in Online applications.
Bar Code Printer In VB.NET
Using Barcode drawer for .NET Control to generate, create barcode image in .NET framework applications.
FIGURE 29.3 Bipolar transistor interface.
Interfacing Digital Inputs
The following sections describe common ways to connect digital inputs to the control electronics (microprocessor, computer, or microcontroller) of your robot.
BASIC INTERFACE CONCEPTS
Switches and other strictly digital (on/off) sensors can be readily connected to control electronics. Figs. 29.8 through 29.10 show a variety of techniques, including direct connection of a switch sensor, interface via a switch debouncer, and interface via a buffer. The buffer is recommended to help you isolate the source of the input from the control electronics.
INTERFACING FROM DIFFERENT VOLTAGE LEVELS
Some digital input devices may operate a voltage that differs from the control electronics. Erratic behavior and even damage to the input device or control electronics could result if you connected components with disparate voltage sources together. So-called logic translation circuits are needed for these kinds of interfaces. Several integrated circuits provide these functions in off-the-shelf solutions. You can create most of the interfaces you need using standard CMOS and TTL logic chips.
14 1 Control 2 7
4011 (1/4) g 3
d Q1 s
Load
14 1 Control 2 7
4011 (1/4) g 3
d Q1 s
Load
FIGURE 29.4 Power MOSFET interface.
+V +12V 14 1 2 7 4011 (1/4) g 3 s d Q1 D1 C1 0.1 D3 d Q3 s g
Direction control
Forward 1 Reverse 0
4011 (1/4)
d g s Q2 D2 D4 Q4
d g s
D1-D4: 1N4002 Q1-Q4: n-channel MOSFET
FIGURE 29.5 Discrete component H-bridge interface.
Enable/PWM Direction Brake
FIGURE 29.6 Packaged H-bridge interface.
2 3 Input
7 741 6 Output
FIGURE 29.7 Non-inverting buffer follower interface.
Microprocessor/ microcontroller input
FIGURE 29.8 Direct connection of switch/digital input.
120K 6 7 555 2
Microprocessor/ microcontroller input
S1 0.1
FIGURE 29.9 Switch debouncer input.
INTERFACING DIGITAL INPUTS 443
Buffer or interver (Schmitt trigger shown) +V or Gnd S1 Microprocessor/ microcontroller input
FIGURE 29.10 Buffer input.
+12vdc (or higher than TTL supply)
+5vdc
10K Input TTL (Any Gate) Output 1K b 2N2222 c e CMOS (Any Gate)
FIGURE 29.11 TTL-to-CMOS translation interface.
Fig. 29.11 shows how to interface TTL (5 volt) to CMOS circuits that use different power sources (use this circuit even if both circuits run under 5 vdc). Fig. 29.12 shows the same concept, but for translating CMOS circuits to TTL circuits that use different power sources.
USING OPTO-ISOLATORS
Note that in both circuits the ground connection is shared. You may wish to keep the power supplies of the inputs and control electronics totally separate. This is most easily done using opto-isolators, which are readily available in IC-like packages. Fig. 29.13 shows the basic concept of the opto-isolator: the source controls a light-emitting diode. The input of the control electronics is connected to a photodetector of the opto-isolator. Note that since each side of the opto-isolator is governed by its own power supply, you can use these devices for simple level shifting, for example, changing a 5 vdc signal to 12 vdc, or vice versa.
ZENER DIODE INPUT PROTECTION
If a signal source may exceed the operating voltage level of the control electronics, you can use a zener diode to clamp the voltage to the input. Zener diodes act like valves that turn on only when a certain voltage level is applied to them. As shown in Fig. 29.14, by putting a zener diode across the V and ground of an input, you can basically shunt any excess voltage and prevent it from reaching the control electronics.
444 INTERFACING WITH COMPUTERS AND MICROCONTROLLERS
+12vdc (or higher than TTL supply)
+5vdc
10K CMOS (Any Gate) Output 1K b 2N2222 c e
Input
TTL (Any Gate)
FIGURE 29.12 CMOS-to-TTL translation interface.
+5vdc
680
4.7K Output
Input
Opto-isolator
FIGURE 29.13 Opto-isolator. Limiting resistor (as needed) Input Zener Output
Zener FIGURE 29.14 Zener diode shunt.
Zener diodes are available in different voltages; the 4.7- or 5.1-volt zeners are ideal for interfacing to inputs. Use the resistor to limit the current through the zener. The wattage rating of the zener diode you use depends on the maximum voltage presented to the input as well as the current drawn by the input. For most applications where the source signal is no more than 12 15 volts, a quarter-watt zener should easily suffice. Use a higher wattage resistor for higher current draws.
Copyright © OnBarcode.com . All rights reserved.