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Input & Output
StamPLC input signal and relay control related APIs and example programs.
Relay Example Program
/*
*SPDX-FileCopyrightText: 2025 M5Stack Technology CO LTD
*
*SPDX-License-Identifier: MIT
*/
#include <Arduino.h>
#include <M5StamPLC.h>
void setup()
{
/* Init M5StamPLC */
M5StamPLC.begin();
}
void loop()
{
static bool relay_state = false;
/* Toggle relay state */
relay_state = !relay_state;
for (int i = 0; i < 4; i++) {
M5StamPLC.writePlcRelay(i, relay_state);
printf("Write Relay %d to %s\n", i, relay_state ? "ON" : "OFF");
delay(500);
}
delay(1000);
}Relay API
writePlcRelay
Function Prototype:
void writePlcRelay(const uint8_t& channel, const bool& state);Function Description:
- Controls writing the relay state for the specified channel
Parameters:
const uint8_t& channel:
- 0-3
const bool& state:
- true: ON
- false: OFF
Return Value:
- null
writePlcAllRelay
Function Prototype:
void writePlcAllRelay(const uint8_t& relayState);Function Description:
- Controls writing the relay state for all channels
Parameters:
- const uint8_t& relayState:
- bit[0:3] -> channel[0:3]
- bit == 1: ON
- bit == 0: OFF
Return Value:
- null
readPlcRelay
Function Prototype:
bool readPlcRelay(const uint8_t& channel);Function Description:
- Reads the relay state for the specified channel
Parameters:
- const uint8_t& channel:
- 0-3
Return Value:
- bool:
- true: ON
- false: OFF
Input Example Program
/*
*SPDX-FileCopyrightText: 2025 M5Stack Technology CO LTD
*
*SPDX-License-Identifier: MIT
*/
#include <Arduino.h>
#include <M5StamPLC.h>
void setup()
{
/* Init M5StamPLC */
M5StamPLC.begin();
}
void loop()
{
static std::array<bool, 8> input_list;
// Read inputs
for (int i = 0; i < 8; i++) {
input_list[i] = M5StamPLC.readPlcInput(i);
}
// Print input reading result
printf("Input: %d, %d, %d, %d, %d, %d, %d, %d\n", input_list[0], input_list[1], input_list[2], input_list[3],
input_list[4], input_list[5], input_list[6], input_list[7]);
delay(1000);
}Input API
readPlcInput
Function Prototype:
bool readPlcInput(const uint8_t& channel);Function Description:
- Reads the state of the specified input signal channel
Parameters:
- const uint8_t& channel:
- channel 0-7
Return Value:
- bool:
- true: HIGH
- false: LOW