Page 487 - Sensors and Control Systems in Manufacturing

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Ni ne
Cha p te r

Program
RAM ROM
Keyboard Display
memory memory

Data address control bus

0 0
1 1
2 2
Sensors Actuators
3 Micro- 3
4 processor 4
5 5
6 6
7 7
Input register Onput register
(port I) (port O)
FIGURE 9.1 Single-board computer.

output response. Registers of this type, which are especially suitable
for signal input and output, are also known as ports.
The system input/output units are connected by a bus system,
through which they can communicate with one another. Bus is the
designation for a system of lines to which several system components
are connected in parallel. However, only two connected devices are
able to communicate with one another at any time (Fig. 9.1).

9.3 Sensors for Input Control
A microcomputer is used for the dual-level input control of a reser-
voir (Fig. 9.2). The level of the liquid is kept constant within the spec-
ified limits. For this purpose, two sensors are placed at the desired
maximum and minimum locations:

Maximum sensing level = maximum limit
Minimum sensing level = minimum limit

Maximum and minimum sensors are installed to recognize the
upper and lower limits. The motor is switched ON when the mini-
mum level has been reached:

Max = 0
Min = 0