MPINO-8A4R-SU

Digital input

8 isolated digital input channels

Eight digital input channels read external switches and sensors reliably, straight from the terminal block.

• D0–D7 inputs

  Eight digital input points in total

• 

  COM0 / COM1 commons

  Two independent input groups

• 

  Optocoupler isolation

  Control circuit protected from field noise

• 

  NPN / PNP sensors

  Works with either sensor wiring convention

Input channel layout

* Example wiring for external switches or sensors (NPN/PNP shared)

Relay output

4 relay output channels (1a1c)

4 relay output channels switch and control external loads reliably.

• 

  D32–D35 outputs

  4 relay contact output points

• 

  4 × 1a1c relays

  Each output is an independent relay contact

• 

  1 output per COM

  Each output has its own COM terminal

• 

  Electrical isolation

  Control and output sides separated by the relay

Output channel layout

* Example wiring for external loads (relay contact output)

Analog inputAnalog Input

4 analog input channels, current or voltage selected per channel by jumper

A0–A3 come out on a 5-pole screw terminal block on the board's left edge, reading GND, A(3), A(2), A(1), A(0) from the top. Every channel ships as a 0–20 mA current input; pull that channel's jumper on the SELECT header and it becomes a DC 0–5 V voltage input. DC 0–10 V can be selected as an option when ordering.

• A0–A3 · 4 channels

  Four 10-bit (0–1023) analog input points

• 0–20 mA by default

  Jumper fitted at the factory · 250 Ω input

• Jumper off → DC 0–5 V

  Selected independently per channel · 100 MΩ

• External reference

  5 V on the VREF pin via analogReference(EXTERNAL)

Analog input terminals

* A 5-pole screw terminal block on the board's left edge, in the order GND · A(3) · A(2) · A(1) · A(0) from the TOP — note that GND is the topmost terminal and A(0) the lowest. One GND is shared by all four channels. The range is set on the SELECT header at board centre, one jumper per channel, all four fitted as shipped.

Temperature inputNTC Temperature

2 NTC temperature channels on their own connectors

A(4) and A(5) each take an NTC 3950 10 kΩ thermistor and read −40 to 120 °C in 0.1 °C steps. They sit on two separate connectors at the board's upper right, apart from the analog input terminals, and have no polarity — the two leads are interchangeable.

• A(4) · A(5)

  Two temperature channels on A4 (D49) / A5 (D50)

• NTC 3950 10 kΩ

  10 kΩ at 25 °C, B constant 3950 K

• −40 to 120 °C

  0.1 °C resolution (over 0–40 °C)

• Own 2-pin connectors

  Separate from the analog terminals · no polarity

NTC temperature connectors

* Two 2-pin connectors at the board's upper right, silkscreened A(4) and A(5) under a shared NTC-TEMP legend — 2 pins per channel. The NTC input has no polarity, so the two leads are interchangeable.

High-speed pulse outputPWM Output

6 PWM output points on two 4-pin headers, driven by two timers

D21, D22, D23 (Timer3) and D26, D27, D28 (Timer1) come out on two 4-pin headers — three outputs plus a GND on each. The output swings LOW DC 0 V to HIGH DC 5 V at up to 30 mA per point, and analogWrite() takes a duty of 0–255 that extends to 0–65535 once the timer registers are changed.

• 6 PWM points

  Two 4-pin headers · three outputs + GND on each

• Two timer groups

  D21–D23 = Timer3 · D26–D28 = Timer1

• 8-bit → 16-bit duty

  0–255 by default, 0–65535 after the register change

• DC 5 V · 30 mA

  LOW 0 V / HIGH 5 V · up to 30 mA per point

Pulse output headers and duty

* Two 4-pin headers on the board's right edge. The upper one is silkscreened PWM over 26 · 27 · 28 · GND, the lower one 21 · 22 · 23 · GND, and each header carries its own GND pin. The two headers are driven by different timers, so the timer a pin belongs to decides which pins can change together.

External interruptInterrupt

Count high-speed pulses and read a rotary encoder from the interrupt inputs

CLK (D24), DIO (D25), SCL (D18) and SDA (D19) are the four interrupt inputs, and each of them carries a built-in 10 kΩ pull-up. attachInterrupt() catches the edge, so the same inputs count high-speed pulses or read a rotary encoder's rotation and direction, at up to 50 kHz. Two pins on the pulse output header, D22 and D23, can serve as interrupts as well.

• 4 interrupt inputs

  CLK (D24) · DIO (D25) · SCL (D18) · SDA (D19)

• High-speed pulse counting

  Counted in the ISR · inputs up to 50 kHz

• Rotary encoder input

  A CLK edge samples DIO to get the direction

• 10 kΩ pull-ups built in

  On all four inputs · DC 0–5 V · HIGH recognised from 3 V

• Two more: D22 and D23

  These two are pins on the pulse output header (21 · 22 · 23 · GND) and can be used as interrupts as well. They have no pull-up or pull-down of their own, so add an external one if the signal needs it — and while a pin is used as an interrupt it cannot output PWM.

What the interrupts are for

volatile unsigned int count = 0;

void setup() {
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(CLK), countFunc, RISING);
}

void loop() {
  noInterrupts();
  unsigned int snapshot = count;
  interrupts();
  Serial.println(snapshot);
}

void countFunc() { count++; }

volatile long encoderValue = 0;

void setup() {
  Serial.begin(115200);
  attachInterrupt(digitalPinToInterrupt(CLK), updateEncoder, RISING);
}

void loop() {
  Serial.print("Encoder Value: ");
  Serial.println(encoderValue);
  delay(500);
}

void updateEncoder() {
  if (digitalRead(DIO)) { encoderValue++; }
  else { encoderValue--; }
}

* On the left the pulse source's output goes to the CLK terminal and its ground to GND, and every rising edge adds one in the interrupt service routine. On the right the encoder's two phases sit 90° apart, so the level of DIO at a rising CLK edge is the direction of rotation.

* Two 4-pin connectors on the board's right edge, drawn in the order the pins are silkscreened. CLK is D24 (INT6), DIO is D25 (INT7), SCL is D18 (INT0) and SDA is D19 (INT1), and all four carry the built-in 10 kΩ pull-ups. The FND (7-segment) accessory and I²C use the same pins, so they cannot be used while those pins serve as interrupts.

CommunicationRS-485 · I²C

RS-485, I²C and a USB serial port

RS-485 runs on a MAX13487EESA+ AutoDirection transceiver, so there is no direction-control pin to handle in code — call Serial1.begin() and transmit. Modbus RTU works as either master or slave. I²C brings its own 10 kΩ pull-ups for a DS3231 RTC or a character LCD, and the USB port handles upload and debugging.

• RS-485 · 1 channel

  MAX13487 AutoDirection · no direction pin in code

• Modbus RTU

  Works as master or slave

• I²C · 1 channel

  10 kΩ pull-ups built in · RTC, character LCD

• USB serial

  Upload and debug over the USB port

RS-485 two-wire bus

* The 4-pole screw block at the board's top edge, right of the digital input terminals, in the order 485+ · 485− · +5V · GND from the left. The schematic ties 485+ to the transceiver's A and 485− to its B. To reach RS-232 or UART instead, use the M-CONV converter (sold separately).

* The I²C connector is silkscreened I2C/ENCO/INT — it doubles as an interrupt and encoder input — and reads GND · +5V · SDA · SCL. The upload port is the mini USB-B connector silkscreened UPLOAD at the board's upper left.