This invention relates to an apparatus which controls an elevator by the use of an electronic computer.
FIG. 5 is a block diagram exemplarily showing a prior-art control apparatus for an elevator disclosed in the official gazette of Japanese Patent Application Laid-open No. 58-144072.
Referring to the figure, numeral 1 designates a CPU (central processing unit), and numeral 2 designates signal lines such as an address bus, data bus and control bus. A memory 3 stores a program for controlling the elevator, a memory 4 stores control information items peculiar to a building, such as the number of floors to be served and a stand-by floor during a slack hour, and a memory 5 stores the calculated results of the CPU 1. An elevator appliance 6 is installed in each of the cages and halls of the elevator. A converter 7 performs the conversion of information between the CPU 1 and the elevator appliance 6 (such as voltage level conversion, analog/digital conversion and serial/parallel conversion).
In the prior-art elevator control apparatus constructed as described above, the CPU 1 executes operations on the basis of the information of the memory 4 and the information of the elevator appliance 6 received through the converter 7, in accordance with the program stored in the memory 3 and while utilizing the memory 5, whereupon it controls the elevator appliance 6 through the converter 7.
Usually, the memory 3 is a read-only nonvolatile memory (hereinbelow, termed "ROM") the stored contents of which are held even when power supply is cut off, while the memory 5 is a volatile memory (hereinbelow, termed "RAM") the stored contents of which are held only while a supply voltage is fed, and from and into which data can be read and written. As the memory 4, a ROM which is similar to the memory 3 or a setting unit in which the "on" and "off" states of a switch correspond to binary numbers "1" and "0" respectively was common in the past, but a nonvolatile memory (for example, EEPROM) from and into which data can be electrically read and written and the stored contents of which are held even when power supply is cut off has come into use in recent years. The reasons therefor are as follows: With the ROM, in a case where the control information is to be altered due to change in the stand-by floor during the slack hour or increase in the number of floors of the building, the ROM needs to be replaced, and this expends time and labor. On the other hand, with the setting unit, one switch corresponds to one bit, and hence, the cost relative to the amount of information is high. In contrast, when the EEPROM is employed by way of example, data can be rewritten, so that the ROM need not be replaced even in the case of altering the control information, and moreover, the cost of the EEPROM relative to the amount of information is low.
In the prior-art elevator control apparatus as described above, in the case where the ROM from and into which data can be electrically read and written is used as the memory 4 for storing the control information peculiar to the building, it has a single area for storing the control information items. Therefore, when any control information has been altered, the whole storage area needs to be checked for acknowledging the absence of an alteration error. This leads to the problems that labor is expended, and that a check error is prone to arise because the number of information items to be checked is large.