If I specify “pull_up_down=GPIO.PUD_DOWN”, there seems to be no change in the bounce. I tried using the Pi’s built-in pull up-down resistors. When a given piece of equipment is on, I expected that GPIO pin to constantly show ‘0’, but it still bounces between ‘0’ and ‘1’. When none of the pieces of equipment is active, the readings on the GPIO pins bounce between ‘0’ and ‘1’. I have connected each output channel from the SCADA system to a GPIO pin on the Pi. I have confirmed this with a meter and continuity tester. When the piece of equipment is on, the voltage on the channel is zero as the channel is connected to ground. When the piece of equipment is off, there is a voltage of between 1.8V and 3.5V on each respective channel. I am trying to read nine outputs from the SCADA system which are on/off signals that represent the status of various pieces of equipment. I am trying to interface a Raspberry Pi Model 3B+ with an old (1980’s vintage) SCADA system.
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