Hitachi, Ltd.

Katsuhiro Fujiwara

Takayuki Oshiga

Toshiro Kasahara

Yasuo Morooka

Masato Shibayama

Masahiro Kayama

Kazuyuki Tsuburaya

Kazunori Umeda

Michiaki Kotsuka

Atsushi Itoh

Mitsusuke Okamura

Hiromi Oshida

Kazuyoshi Osako

An input/output device has a processor which processes data strings received by the device. When a data string is received, it is passed to a serial interface and a timing means. The serial interface generates a signal which interrupts the existing processing by the processor and causes the process to start processing of the newly received data string. At the same time the timing means measures the length of the data string and compares it with a predetermined length set by user-controllable data setting means. If the data string length reaches the predetermined length, the processor is triggered to stop processing the new data string and to recommence the processing it was performing prior to interruption. The unprocessed part of the new data string is stored in a memory. In this way, urgent data strings, which are generally short, are processed rapidly and longer data strings are processed after the urgent data strings. It is not necessary for the data string to contain any information to identify its length.

Input/output device and a control system incorporating such a device

In a sequence controller which is capable of debugging a program including a plurality of sequence programs, a program head code is provided in the program to identify respective sequence programs. In executing the program, the number of sequence programs which are executed is counted by detecting the program head codes associated therewith. Thus, sequence processing can be effected for a predetermined number of sequence programs by stopping the processing of the sequence when the count of the detected program head codes becomes equal to the predetermined number. In addition, it is possible to count only those sequence programs which satisfy a certain condition, such as sequence programs which require a particular operation or relate to a particular control element. In this way, debugging of the program is facilitated.

Sequence controller

A built-in insulating element for electrically insulating a process portion from a control object and for transmitting a process result to the control object is provided in the output portion for transmitting the process result of a sequence controller to the control object. Further, a noise preventive element is provided in the output portion for preventing a noise voltage from coming in from the control object side and damaging the insulating element.

Apparatus for insulating and preventing noise in the output of a

Programmable controller

A programmable sequence controller has indicator lamps for displaying the status of the respective input and output signals. The indicator lamps are respectively coupled with signal input and output terminals through a connector, and are included as in a panel which cover the front surface of the signal input and output terminals.

Programmable sequence controller

Data processing between selected I/O terminals is switched between processing by direct access to the I/O terminals and processing by indirect access through an image memory having a one-to-one correspondence to the I/O terminals.

Programmable sequence controller having indirect and direct input/output

The states of the signals inputted to a programmable sequence controller or outputted from the programmable sequence controller are stored by a few scanning operations. A check is made to see if a combination of input and output signals which cannot be generated during one scanning operation in the normal operating mode exists in that memory content or not, thereby investigating causes of the occurrence of abnormalities.

Sequence control apparatus

In a sequence control apparatus using a microprocessor performing its processing of operation in terms of one word as the unit therefor, a change indicating signal from a process condition detecting or measuring instrument connected to an I/O unit is taken into the microprocessor in a form combined with predetermined pattern data. With the resulting composite data, the contents of those bits of an accumulator in the microprocessor which do not correspond to the change indicating signal can be optionally processed.

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Sakurashi, Japan

Katsuhiro Fujiwara