Abstract: An input/output unit is a test pulse width calculation device for calculating a time width of a test pulse for use in a failure diagnosis test of a PLC. The input/output unit includes a memory that stores a threshold for detection of noise superposed on a signal to be input to an input circuit of the PLC, and a processor. The processor includes a voltage value acquirer and a test pulse width calculator. The voltage value acquirer acquires a measurement value of voltage in an input path of the signal to be input to the input circuit. The test pulse width calculator calculates, based on the measurement value of voltage and the threshold, a reference noise width that is a reference for calculating a test pulse width, and calculates the test pulse width that is larger than the calculated reference noise width.

Abstract: A programmable logic controller system has: an input unit system section in which plural input units are combined; a CPU unit system section in which plural CPU units are combined; and an output unit system section in which plural output units are combined. Each system section has: a setting retaining unit to retain a setting indicating whether to use any of the plural units alone or use the plural units in a multiplexed manner; and a comparing unit to make a comparison of processed data between the plural units when the setting indicates using the plural units in a multiplexed manner, to send the processed data if the comparison result indicates consistency, and to perform an error process if the comparison result indicates inconsistency. In the setting retaining unit, whether to use alone or in a multiplexed manner is set based on an externally-input setting instruction.

Abstract: To provide a sequencer system including a plurality of bases. The plurality of bases are configured by a fundamental base and a plurality of stages of extension bases, the fundamental base being installed with a control unit. The control unit is configured to enable transmission of a HOP designation packet toward the bases, number of HOPs being designated for the HOP designation packet. Upon reception of the HOP designation packet with the number of HOPs being other than 0, each of the bases subtracts the number of HOPs by one, and transfers the HOP designation packet to the base connected to a subsequent stage. Upon reception of the HOP designation packet with the number of HOPs being 0, each of the bases determines that the HOP designation packet is a packet directed to the base itself.

Abstract: A programmable logic controller system has: an input unit system section in which plural input units are combined; a CPU unit system section in which plural CPU units are combined; and an output unit system section in which plural output units are combined. Each system section has: a setting retaining unit to retain a setting indicating whether to use any of the plural units alone or use the plural units in a multiplexed manner; and a comparing unit to make a comparison of processed data between the plural units when the setting indicates using the plural units in a multiplexed manner, to send the processed data if the comparison result indicates consistency, and to perform an error process if the comparison result indicates inconsistency. In the setting retaining unit, whether to use alone or in a multiplexed manner is set based on an externally-input setting instruction.

Abstract: To provide a sequencer system including a plurality of bases. The plurality of bases are configured by a fundamental base and a plurality of stages of extension bases, the fundamental base being installed with a control unit. The control unit is configured to enable transmission of a HOP designation packet toward the bases, number of HOPs being designated for the HOP designation packet. Upon reception of the HOP designation packet with the number of HOPs being other than 0, each of the bases subtracts the number of HOPs by one, and transfers the HOP designation packet to the base connected to a subsequent stage. Upon reception of the HOP designation packet with the number of HOPs being 0, each of the bases determines that the HOP designation packet is a packet directed to the base itself.