Serial interfaces

These two transducer pairs are activated alternating. For this purpose an ultrasonic instrument is combined with a two channel multiplexer. Figure 8 presents a modified standard instrument USN52 which also implies a modified software. This system performs four measurements per second - alternating the velocity and the thickness are determined. The probe can be scanned over the surface and in every position both, the velocity and the wall thickness are indicated Using the serial interface of the instrument finally a two-dimensional map of velocity or thickness can be generated. 

Serial Interfaces Some very important measurement devices cannot be reasonably interfaced via either analog or pulse inputs. Two examples are the following ... 

One approach to interfacing with such devices is serial interfaces. This involves two aspects ... 

Hardware inteiface. The RS-232 interface standard is the basis for most serial interfaces. 

One advantage of serial interfaces is that two-way communication is possible. For example, a tare command can be issued to a load cell. 

Olsen, E. Serially interfaced gas chromatography/Fourier Transform infrared spectrometer/ion trap detector. Finnigan MAT IDT 35. 

Monolithic sensor systems, however, offer advantages such as low power consumption or reduced packaging efforts. Integration of an on-chip serial interface reduces the number of bonding wires, especially in the case of an integrated multisensor array. Taking into account the mass-production facilities with estabhshed microelectronic and microtechnological processes, commercialization of monoHthic... 

The plotter Within this field, the choice was much simpler for very few serious firms are developing this type of peripheral, and speaking money, all of them are in the same region. For various reasons, we chose the HP 7225 A Hewlett-Packard plotter. It can draw and write and, of course, all the figures of this article were entirely designed using the HP 7225 A plotter connected to the Apple II Plus microcomputer. The interface used for this connection is a RS 232 C Serial Interface. 

The RS-232-C standard defines a serial interface which is commonly used. In its minimum configuration it is possible to transmit data over 15 meters with only three wires. For large distances a modem would be necessary. Data transmission is performed by sending the individual bits of a data byte one after the other. The data bits are enclosed by special bits (start bit, parity bit, stop bit) which provide proper synchronization and error detection in the receiver. The form of the transfer is called the protocol. This protocol defines the baud rate (bits per second = baud), the number of stop bits and an optional parity bit. Figure 8.10 shows an example of transmitted data. A logical 0 is transmitted by a voltage level of +3.. + 12 V and a... 

Figure 3 Functional scheme of recording block (microcontroller) 1- GPU, 2-ROM, 3-RAM, 4- timer, 5 - power supply, C - bus, 7-11 - PIA, 12 - serial interface, 13- key-board/display, 14-17 - voltmeter, 18 - P-sensor, 19- T-sensor, 20- V-sensor, 21- sample, 22 - port RS-232S (communication with computer).

Wide area networks to other sites Local area networks/intranet Serial interface protocols Message packet formats File transfer protocols... 

If parallel communications are similar to taking the interstate, then serial communications are similar to taking a country road. In serial communications, each bit of data is sent one after another (single file, if you will) down one wire, and returns on a different wire in the same cable. There are three main types of serial interfaces available today Standard serial. Universal Serial Bus (USB), and FireWire. 

Because of it s higher transfer rate, flexibility, and ease of use, most devices that, in the past, used serial interfaces, now come with USB interfaces. It s rare to see a newly introduced PC accessory with a standard serial interface cable. For example, PC cameras (like the Logitech QuickCam) used to come as standard serial-only interfaces. Now you can only buy them in the stores with USB interfaces. 

A floppy controller is not a complicated device. The early controllers were large expansion boards that usually contained an Intel 8272 or Zilog 765 controller chip. As this book is being written, you can buy a card that contains the floppy controller, two serial interfaces, parallel and game interface ports, and disk interface for about 35. 

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