Hitachi, Ltd.

Toshiro Kasahara

Katsuhiro Fujiwara

Takayuki Oshiga

Atsushi Itoh

Yoji Ichiyasu

Hiromi Oshida

Oshiga Takayasu

Katuhiro Fujiwara

Mitsusuke Okamura

Sequence 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

Growing community of inventors

Narashino, Japan

Toshiro Kasahara