US RE50,428 E1
Input module of industrial control apparatus
Takaaki Maekawa, Chita-gun (JP); and Takashi Hanai, Toyokawa (JP)
Assigned to DENSO WAVE INCORPORATED, Aichi-Pref. (JP)
Filed by DENSO WAVE INCORPORATED, Aichi-Pref. (JP)
Filed on Mar. 19, 2024, as Appl. No. 18/609,526.
Application 18/609,526 is a reissue of application No. 16/935,260, filed on Jul. 22, 2020, granted, now 11,300,951, issued on Apr. 12, 2022.
Claims priority of application No. 2019-138794 (JP), filed on Jul. 29, 2019.
Int. Cl. G05B 23/02 (2006.01); H04L 12/40 (2006.01)
CPC G05B 23/0221 (2013.01) [H04L 12/40039 (2013.01)] 6 Claims
OG exemplary drawing
 
1. An input module of an industrial control apparatus comprising:
an input circuit to which a digital signal from an external source is input, the input circuit outputting a binary signal as an internal signal; and
a determination unit determining a level of the digital signal based on the internal signal output from the input circuit, and the determination unit outputting a determination result of the digital signal to an external device, wherein
the input circuit includes:
an OR [ AND ] circuit receiving the digital signal and a clock signal, the OR [ AND ] circuit outputting a logical sum [ product ] signal indicating a logical sum [ product ] of the digital signal and the clock signal, the clock signal having a binary level switching at a predetermined cycle; and
a signal output unit including a switching element, a first main terminal of the switching element being connected with a first supply line that supplies a first voltage corresponding to a high level of the internal signal, a second main terminal of the switching element being connected with a second supply line that supplies a second voltage corresponding to a low level of the internal signal, the switching element is in an on state during a high level of the logical sum [ product ] signal and is in an off state during a low level of the logical sum [ product ] signal, the signal output unit outputting a signal obtained at the second main terminal of the switching element as the internal signal, and
the determination unit:
determines that the digital signal has a low level when the low level of the internal signal continues for a certain time period;
determines that the digital signal has a high level when the internal signal switches from the low level to the high level and then switches to the low level again; and
determines an occurrence of a fixing failure when the internal signal switches from the low level to the high level and then fails to switch to the low level again [ ; and
wherein the external device, which the determination result determined by the determination unit is output to, is provided by a central processing unit module;
wherein the central processing unit module controls an operation of a control target and the control target is configured to stop an operation in response to an activation of an emergency stop switch of the control target;
wherein the level of the digital signal switches in response to the activation of the emergency stop switch of the control target;
wherein, when a level of the internal signal repeatedly switches within a period shorter than a half cycle of the clock signal, the determination unit executes an interpolation process and determines that no level switch occurs in the internal signal;
wherein, when the determination unit continuously executes the interpolation process for a set time period, the determination unit stops a determination of the level of the digital signal and outputs, to the central processing unit module, a determination result that is the same as a result in a case of the activation of the emergency stop switch] .