read barcode from image c#.net RS-232 LINK 159 in Software

Generator Code 128 Code Set A in Software RS-232 LINK 159

RS-232 LINK 159
Decode Code 128 Code Set B In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Create Code 128C In None
Using Barcode generation for Software Control to generate, create Code 128C image in Software applications.
MSB Original Byte D7 D6 D5 D4 D3 D2 D1
Recognizing Code 128 In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Print USS Code 128 In Visual C#.NET
Using Barcode encoder for VS .NET Control to generate, create Code 128 Code Set C image in Visual Studio .NET applications.
LSB D0
Making Code-128 In .NET
Using Barcode printer for ASP.NET Control to generate, create Code128 image in ASP.NET applications.
Code-128 Generator In Visual Studio .NET
Using Barcode drawer for VS .NET Control to generate, create Code 128 Code Set B image in .NET framework applications.
Transmitted Sequence
Code 128 Generator In Visual Basic .NET
Using Barcode encoder for VS .NET Control to generate, create USS Code 128 image in .NET applications.
UPC-A Supplement 5 Drawer In None
Using Barcode creation for Software Control to generate, create Universal Product Code version A image in Software applications.
Start Bit
Generate Barcode In None
Using Barcode printer for Software Control to generate, create bar code image in Software applications.
Drawing Barcode In None
Using Barcode generator for Software Control to generate, create bar code image in Software applications.
D7 Parity Stop Stop Bit Bit Bit Transmitted Last Optional Optional
Encoding GS1-128 In None
Using Barcode encoder for Software Control to generate, create USS-128 image in Software applications.
Encode GTIN - 13 In None
Using Barcode encoder for Software Control to generate, create EAN 13 image in Software applications.
Transmitted first
2 Of 5 Industrial Drawer In None
Using Barcode drawer for Software Control to generate, create 2/5 Industrial image in Software applications.
Drawing GTIN - 128 In .NET
Using Barcode encoder for Visual Studio .NET Control to generate, create EAN128 image in VS .NET applications.
FIGURE 7.2 How the data is reorganized and extra bit attachments added to the original bit sequence in asynchronous serial data transmission.
Paint GS1 DataBar Truncated In Java
Using Barcode printer for Java Control to generate, create GS1 DataBar-14 image in Java applications.
Barcode Printer In None
Using Barcode creator for Microsoft Word Control to generate, create bar code image in Office Word applications.
T= Bit Time Voltage corresponding to logic low
Encode UPC - 13 In VS .NET
Using Barcode creator for .NET framework Control to generate, create European Article Number 13 image in .NET applications.
Generate Barcode In Objective-C
Using Barcode maker for iPhone Control to generate, create bar code image in iPhone applications.
+3V to +12V
Recognizing Code-39 In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
Printing ECC200 In C#
Using Barcode creation for Visual Studio .NET Control to generate, create Data Matrix ECC200 image in Visual Studio .NET applications.
Marking Start Bit D0 Level -3V to -12V
One byte transmission D2 D3 D4 D5
D7 Stop Bit
Voltage corresponding to logic high
FIGURE 7.3 Voltage levels on the RS-232 serial transmission. The wave form is illustrated without any parity bit and one stop bit.
While Figure 7.3 illustrates the voltage levels on an RS-232-compatible line, it is possible to connect to AVR devices without the use of RS-232 level converters. Though in that case, the voltage transmission won t be RS-232 compatible (Figure 7.4). It is also advisable to use this configuration with very short wire links (few inches). For true RS-232 compatibility, it is necessary to use one of the many RS-232 line driver/receiver chips illustrated in Table 7.1. Using these driver chips, one can safely connect maximum cable lengths up to 15 meters. The table is not exhaustive, though. The RS-232 standard is a complex standard and has many signal lines. Originally, the standard specifies a 25-pin D type connector as well as a 9-pin D type connector with all the signals. Of these signals, it takes only TxD, RxD, and Gnd to put together a simple duplex RS-232 communication link. Most controller chips (including some of the processors in the AVR family) are also equipped with a bare-minimum serial interface which includes only TxD and RxD signal lines. Other signal lines of the interface are called handshake lines, which are used by two devices to receive data correctly and in a regulated manner. For smooth data transfer between two devices, the RS-232 standard uses the concept of DTE (Data Terminal Equipment) and DCE (Data Communication Equipment). The pin
160 COMMUNICATION LINKS FOR THE AVR PROCESSOR
AVR TxD RxD
AVR RxD TxD
RS-232 Receiver RS-232 Transmitter AVR TxD RxD RxD TxD AVR
Rx/Tx driver pair usually available in a single chip
RS-232 Transmitter RS-232 Receiver
FIGURE 7.4 Connecting an AVR device to another AVR or any other serial device.
outs and function names referred to in Table 7.2 are with respect to the DTE. The DCE has the same connector pinout, except the direction of the pins reverses. Thus pin 2 of a 9-pin connector on a PC configured as DTE is RxD as an input, while on a modem with a 9-pin connector seen as a DCE, this pin is still called RxD, except it is an output. While we won t be using most of the handshake lines in the rest of the book for any real handshake purpose, these handshake signal lines can be used for another interesting functionality: to provide power to our AVR circuits! While connecting AVR circuits to full function RS-232 ports on a PC, we can use signal lines RTS and DTR to provide supply voltage for the microcontroller. The AVR family has many processors equipped with on-chip serial port functionality. With a suitable line driver and receiver component (refer again to Table 7.1), it is possible to create a RS-232 link.
7.3 RS-422/423 Link
The RS-422/423 communication differs from the RS-232 in only the way the bit logic levels are translated into line voltages, the maximum possible data rates, and the length of the
RS-485 LINK 161
TABLE 7-1
SOME RS-232 LINE DRIVER AND RECEIVER ICS PART NUMBERS COMMENTS
MANUFACTURER
Maxim Maxim Dallas Dallas Intersil Analog dev.
MAX212 MAX232 DS232 DS275 HIN203 ADM232
low power, 3 V operations, 3 Tx and 5 Rx channels, up to 120 Kbps. 5 V operation 2 Rx, 2 Tx channels MAX232 compatible Line powered, half duplex (i.e., either transmit or receive at a time) No capacitors required!, up to 120 kbps MAX232 compatible
TABLE 7-2 25-PIN
RS-232 SIGNALS AND CONNECTOR PINOUTS 9-PIN NAME AND FUNCTION DIRECTION
1 2 3 4 5 6 7 8 20 22
3 2 7 8 6 5 1 4 9
Gnd TxD,Transmit Data RxD, Receive Data RTS, Request To Send CTS, Clear To Send DSR, Data Set Ready Gnd DCD, Data Carrier Detect DTR, Data Terminal Ready RI, Ring Indicator In Out In Out In Out In In
cable. RS-422 uses a differential, balanced protocol for communication and is good for up to a maximum of 10 Mbits/s and up to a distance of about 1000 meters (not at the maximum speed though). Figure 7.5 illustrates a RS-422 link. Many manufacturers make RS-422 drivers, and MAXIM s MAX488/490 ICs are quite good (Figure 7.6).
Copyright © OnBarcode.com . All rights reserved.