ESP32 PLC 21: ESP32 PLC with 21 I/O, Ethernet, Wi-Fi and RS-485
The ESP32 PLC 21 is an industrial controller from Industrial Shields built on the dual-core ESP32. It has 13 inputs (6 analog 0-10 V) and 8 outputs (3 analog/PWM), Ethernet, Wi-Fi, Bluetooth LE, RS-485 and RS-232, plus a real-time clock, and mounts on a DIN rail. It is programmed in C++ with the Arduino IDE and suits machine monitoring, data acquisition and control panels that mix analog sensors with digital signals.
You are viewing the FLEX version. Configurable: add one board for LoRa, 4G or CAN.
See CORE Standard configuration, ready to shipDocuments
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Technical specifications
| Processor | ESP32 dual core, up to 240 MHz, 16 MB flash, 520 KB SRAM |
|---|---|
| Inputs | 13: 6 analog/digital (0-10 V, 11-bit) and 7 digital optoisolated, 5 to 24 Vdc, 2 with interrupt |
| Outputs | 8: 3 analog/digital/PWM (0-10 V, 12-bit), 5 digital optoisolated, 5 to 24 Vdc |
| Ethernet | 1 x 10/100 Mbit, RJ45 |
| Wireless | Wi-Fi 2.4 GHz, Bluetooth LE |
| Serial and buses | RS-485 half duplex with 120 Ω termination, RS-232 and TTL serial selectable by DIP switch, I2C, SPI |
| Real-time clock | DS3231 with backup battery (CR1216 or CR1220) |
| Programming | Arduino IDE with the Industrial Shields ESP32 boards package, USB or Ethernet |
| Power supply | 12 to 24 Vdc with polarity protection |
| Mounting and protection | DIN rail TS35, IP20, inside a cabinet |
| Expansion | One optional communication board: 4G LTE-M/NB-IoT (u-blox SARA-R412M), LoRa (EU, US or Asia band) or CAN (MCP2515). I2C expansion up to 127 modules |
Projects built with the ESP32 PLC 21
Field-tested examples with code from the PLC Solution Library.
- Modbus RTU master over RS-485See the example
- Offline-first MQTT data logging with SD cardSee the example
- NTP-synced hardware RTC for timestampsSee the example
- HTTP client to read machine XML dataSee the example
Before you choose the ESP32 PLC 21
How do I program the ESP32 PLC 21?
With the Arduino IDE (1.8.0 or later). Add the Industrial Shields boards URL in Preferences, install the "industrialshields-esp32" package and select the ESP32 PLC 21. Upload through USB, or remotely over Ethernet.
Does it have relay outputs?
No. Its outputs are optoisolated digital and analog/PWM outputs. If you need relays, look at the ESP32 PLC models with relay outputs, such as the 19R, 38R or 57R.
Can the analog inputs read 4-20 mA sensors?
The analog inputs measure 0-10 V with 11-bit resolution. To read a 4-20 mA loop, add a precision shunt resistor (500 Ω turns 20 mA into 10 V) and scale the reading in your program.
Does it support LoRa, 4G or CAN?
Yes, with one optional communication board: LoRa (EU, US or Asia band), 4G LTE-M/NB-IoT or CAN. Wi-Fi and Bluetooth LE are built in.
Can I expand it with more I/O?
Yes. The ESP32 PLC family connects up to 127 expansion modules over I2C, and you can add remote I/O over Modbus RTU with moduleX.