Serial port

When the manufacturer has provided RS-232 output, data can be read directly through a serial port. 

The most versatile data acquisition option is a stand alone data collection unit. At Glidden we use an Elexor Data Logger (S) for this purpose. It has its own microprocessor and BASIC Interpreter and communicates with the computer via the serial port. The unit can be configured with a wide variety of signal processing options. 

In order to collect data via the serial port or A/D in background mode, the computer must initiate a multi-tasked routine. The limitation of this approach is the software overhead it introduces and the risk of data loss should the computer crash. When the data logger is used in background mode, the computer could be turned off and back on while a run is in progress with no loss of data. 

The transmission of data between an ADC or DAC and a computer is usually accomplished by sending one byte at a time along a multiway ribbon cable external bus). The IEEE 488 standard bus has been widely used for this purpose, but other buses are also used. As all bits are handled simultaneously this is known as parallel I/O transmission, the data entering or leaving the computer via a parallel port or by direct connection to the computer s internal bus. Alternatively, one bit at a time can be transmitted along a single line serial I/O transmission). Data enter or leave the computer via a serial port, usually an RS-232C. Serial I/O ports are used for... 

The actual mode of connection between instrument and computer varies depending on the type of signal generated and the design of the instrument. The connection can be made via a serial port, a parallel port, or a USB port. The electronic circuitry required is built into the instrument s internal readout electronics or into an external box used for conditioning the instrument s output signal. In some cases, the instrument will not operate without the computer connection and is switched on and off as the computer is switched on and off. In other cases, the entire computer is built into the instrument. 

Connect the Tl-graph link cable to a free serial port of the Windows computer and to the port on the bottom edge of the TI calculator. 

With GRAPHICAL ANALYSIS running, choose Import from the TI Calculator under the FILE MENU. If the Tl-graph link cable is not connected to the serial port designated in the status box, click on SELECT PORT and choose the correct port for the Tl-graph link cable. 

Polarity Dr Kernchen Propol (fitted with a serial port)... 

The front panel of the controller has two four-digit thumbwheel switches and two lighted pushbutton switches. The thumbwheels determine flow rate (ml/min) and volume to be delivered (ml). One pushbutton switch initiates the pump-refill operation. The other starts the injection, or stops an injection in progress. After power-up or reset, the microprocessor initializes itself and sets up the timing module and serial ports. It then jumps into a looping program that scans the two pushbutton switches and the... 

This system will perform both bolus and constant infusion studies with the microprocessor controller. In addition, variable or exponential infusion studies can be performed by using programs residing in a host computer to calculate constants which are sent to the controller through the serial port. 

Fig. 1. Electronic medication event monitor in the process of communicating stored data from monitor to computer. The transfer occurs without wire connection between the inverted monitor and the communications interface device, which transfers data to MS-DOS-based computers via serial port. A second medication event monitor, with a somewhat larger container size, stands nearby. (Copyright, 1994, APREX Corporation reproduced with permission.)...

The crossbar interconnect is under the control of the microprocessor. The DSPs are programmed remotely, via the microprocessor by the processor s serial port (see section 5.13). The processors all run lock-step and are sample synchronous. Note that only four processors have external memory (and only 64K). This severely limits the reverberation time but in fairness, this machine was not designed for effects processing. Also note that coefficient conversion from real time inputs must take place in the host processor and then be converted into serial form and placed in the specific DSP. 

RS232 serial port or IEEE488 interface bus). The plug-in cards use the computer power supply which tends to contain noise generated by all of the digital pulses generated in the computer. Higher bit conversion would not introduce improved measurement accuracy because of this noise. 

SCSI (small computer system interface, pronounced skuzzy ) search engine security certificate serial communication serial port server servlet set up (verb) setup (noun)... 

Software programs are available to accept data from instruments and transfer it in real time to Excel. For example, SoftwareWedge (TAL Technologies, Inc., 2027 Wallace St., Philadelphia PA 19130) captures RS-232 serial I/O data, parses and filters it to user specifications, and transfers it to Excel for Windows via DDE (Dynamic Data Exchange). Data can be received from several serial ports simultaneously. The user can also define output strings, which can be sent to an instrument to control it directly from Excel. Discussion of this and similar software is beyond the scope of this book specific information can be obtained from the manufacturer. 

The MMU also controls the fast serial port used with the 1571 disk drive (and conceivably with other fast peripherals). It determines the clock speed of the 8502, and controls which of the three microprocessors (6510, 8502, Z80) is in control. And although not supported in ROM, it s possible to have all three microprocessors running by quickly switching between them. 

For most users, the serial port is the major data artery of the computer. As the connection point for disk drives and printers, it s the port through which most information exchanges take place. This is the one port that is the same on the Commodore 128, 64, VIC-20, Plus/4, and 16. Well, almost the same—there are some signal timing differences. (The VIC-20 transfers data at a slightly faster rate than the others, which is why the VIC is listed as incompatible with some Commodore printers, and why the original 1540 disk drive was only for the VIC.) How-... 

Obviously, this port is bidirectional—data can flow both in and out with equal ease. The signal format used to exchange data serially over the six lines provided through this port is unique to Commodore. The format should not be confused with the more standard RS-232 serial communications format used by numerous peripherals RS-232 communication is handled through the user port (see below). The serial port is essentially a stripped-down version of the parallel IEEE-488 port used for most data communications in Commodore s earlier PET/CBM models. As the term serial implies, data can be transferred only one bit at a time (and in only one direction at a time, either in or out). Three of the other lines control the direction of data flow, and whether the signals on the data line are to be interpreted as data or as commands to the peripheral device. The computer s RESET line is also present at this port, which explains why the disk drive resets whenever the computer is turned on or off. 

The reason this isn t often done is that almost all Commodore software expects the printer to be device 4 on the serial port, and in the long run it proves easier to seek a hardware solution to allow you to use the built-in operating system routines as provided in ROM. That way, you don t have to worry about having to load your printer handler routine into memory before you can use it, finding a safe place in RAM to store the handler routine, and so forth. 

If you open a file for reading and try to write to it, or vice versa, you ll get a NOT INPUT FILE or NOT OUTPUT FILE error. If your disk drive is not plugged into the serial port or is not turned on, the computer will tell you DEVICE NOT PRESENT. If you press PLAY on a Datassette (to load a program), and leave it on PLAY, then try to write a file, it will seem to work, but the file isn t actually there. There s a sensor that can tell if a button is pressed, but it doesn t distinguish between PLAY, PLAY/RECORD, or even F.FWD or REWIND. Writing a file while PLAY (but not RECORD) is pressed won t write anything. 

TurboDisk machine language in the computer reads the incoming data from the serial port s DATA and CLK lines, instead of just the DATA line as in normal serial data transfers. Thus, TurboDisk temporarily converts your serial drive into a two-bit parallel drive. When the entire 256 bytes from a disk sector have been transferred into the computer s buffer, data from the buffer is added to the program in memory while the drive is reading the next sector from the disk. 

Which port(s) are used for serial ports (Select all that apply.)... 

B. In most cases, a male DB-25 port will be a serial port. In some cases, you could find some specialized cards that differ, but they are rare. 

B, D. Most commonly, you will use DB-9 and DB-25 connectors for serial ports. 

Almost every computer made since the original IBM PC has at least one serial port. They are easily identified because they have either a DB-9 male (shown in Figure 2.24) or DB-25 male port. Standard serial ports have a maximum data transmission speed of 57KBps and a maximum cable length of 50 feet. 

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