Control method for automatic gathering of status data for distributed type remote I/O control system at start-up
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsAkihiro Yamashita, Junichi Mito
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Abstract
A basic system of an NC unit and a distributed type remote I/O unit executes time division signal transaction through a half-duplex serial communication line, and in case where the distributed type remote I/O can not detect a receiving start state of a transmission frame from the basic system of the NC unit for a specified period of time, output is reset, and the basic system of the NC unit checks a type of and data setting in the distributed type remote I/O unit, and also checks a result for an input/output test and the current situation of communication according to a header pattern of a transmission frame.
Claims20
A control method for a distributed type remote I/O control system including a control unit which is connected to a plurality of distributed type remote I/O units through a serial communication system, said method comprising the steps of:
- executing bidirectional transmission between said control unit and each of said distributed type remote I/O units using time division communication;
- and
- automatically executing communications between said control unit and said remote units in an off-line status communication mode which is different from an on-line communication mode, when operation of said control system is started, to determine a type of said remote I/O unit and data set in said distributed type remote I/O unit,
- wherein switching from said off-line status communication mode to said on-line communication mode, or switching from said on-line communication mode to said off-line status communication mode, is executed by setting a mode select bit in said remote I/O units, switching between on-line status communication and off-line status communication modes is executed by sequentially synchronizing each of the plurality of distributed type remote I/O units, and a status bit is set in said control unit indicating completion of reception of signals for status of each of said distributed type remote I/O units is set after switching modes so that said control unit recognizes completion of reception of status signals.
Dependencies are inferred from the claim text.