Analogue outputs

Figure 2. Schematic representation of the reactor system computer-controlled pumps (PI, P2) pump controllers (fc) reactor (CSTR) reception vessel valves (S1-S4) monomer and initiator storage vessels (Tl, T2). (a) Digital input from GPC injection valve (b) analogue output from GPC (c, d) digital outputs to recorder chart drive and event marker (e, f) analogue outputs for pump set-point adjustment (g,h) reactor feeds (i) reactor output (j-m) digital outputs to reception system valves (n) manual sampling of products by GPC,...

In this series of instruments for analytical electrochemistry, Philips also supplies the microprocessor-controlled PW 9527 digital conductivity meter with 16 push-buttons and on the rear an analogue output for connection to a recorder and a 25-way connector providing a two-way RS 232 serial connection (see Philips leaflet 9498 362 9326). 

Modem washing machines work with this type of pressure sensors with analogue output In such machines the software can be used to set any desired water level. 

Mettler produce two automatic titrimeters the DL 40 GP memotitrator and the lower-cost DL 20 compact titrator. Features available on the DL 40GP include absolute and relative end-point titrations, equivalence point titrations, back-titration techniques, multi-method applications, dual titration, pH stating, automatic learn titrations, automatic determination of standard deviation and means, series titrations, correction to printer, acid balance analogue output for recorder and correction to the laboratory... 

Four serial (RS232) ports are provided for flexible communications to other instruments, i.e. autosamplers. In addition, five analogue inputs, tvsro analogue outputs and 3 TTL input/outputs are provided to ensure complete flexibility. These allow auxihary instruments under direct control and the abihty to process data generated by these in real time. These features extend the range of facihties on these expensive but worthwhile analytical techniques. There is no doubt that future developments in computing will continue to have a radical impact on these instrumental systems. 

A common feature of smart devices is the ability, either to transmit the normal 4-20 mA analogue output (which is digitally linearised and compensated where necessary), or to provide digital communication with other devices as desired. Digital communication with a smart transmitter can be implemented from a microprocessor within the control room, or by the use of a hand-held terminal. The latter can be inserted at any point within the 4-20 mA current loop and instructions to change the range, calibration, etc. can be sent to a specific smart device(l00>. 

Evaluation. The evaluation was carried out by reflectance using a Zeiss PMQ II chromatogram spectrophotometer (Zeiss, Oberkochen), with a direct link of the analogue output to an IBM 1800 process control computer. 

Figure 6.7 Oxygen analyser for gassy coal mines (Group I). Continuous monitoring of the oxygen content in air (e.g. behind fire dams, in panel entries, in gangways). Type of protection EEx ia I Certificate BVS 90.B.1136 Measuring range 0-25% (v/v) 02 Power supply 8... 16.5 V, max. 65 mA Outputs (0-25% (v/v) 02) Analogue output 10-100 mV Frequency shift output 6-15 cps.

Type 5. This Involves the automation of data acquisition and treatment in a traditional analytical Instrument —even a balance can be the subject of automation. As shown In Fig. 1.8, a microcomputer connected on-line with the analogue output of the Instrument ensures the automation of this stage of the... 

Today s laboratories —particularly the larger ones— use a variety of intelligent, microprocessor-controlled, instruments with analogue output and (micro)computers interfaced to one another. It is the fashion in which the interfacing Is done that ensures efficient laboratory computerization (automation). Ziegler [31] established three categories of computerized configurations, namely (Fig. 2.14) ... 

TA apparatus without computers is also used where the analogue output signal is plotted using a chart recorder. Data are accumulated on chart paper and calculations performed manually. The quality of the data obtained is not diminished in any way. The accuracy of the results is the same provided that the apparatus is used properly and the data are analysed correctly. Some in... 

The AD-interface connecting the analyser and the data unit is an 8-channel serial AD-interface with 12-bit resolution. The ADC is based on a Linear Technology chip (LTC1290) and requires only a few additional components (a print board, complete with all components can be purchased for about 50 US from Conrad Electronic, D-92240 Hirschau). This interface is connected to a maximum of 8 spectrophotometer analogue outputs (or other instruments, e.g., an attached conductivity sensor) and to a serial port of the PC. One of the analogue inputs reads the sampler status. A serial ADC allows longer distance between wet analysis and dry data treatment (about 15 m). If parallel ADC interface cards mounted in the computer are used, the wet-analyser and computer have to be close together (less than 5 m). No additional hardware is required. 

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