I see OPENPLC support ESP8266.
The disadvantage of ESP8266 is, that just one ADC Channel is available.
Is it planned to support more channels with an external ADC?
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You can simply add more ESP8266 to your program. The OpenPLC can work with multiple ESPs at the same time. Just use a different DEVICE_ID for each ESP. So, if you need 3 ADC channels, just use 3 ESP8266. They're so cheap that might be about the same price as buying and external ADC anyway! [smile]
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Hi all,
thiagoralves ESP32 is out! and looks that it  will be a fantastic core for doing PLC work with openplc!. It has 2 DACs, ethernet, CAN, among other things. It looks the best candidate for "REAL INDUSTRIAL STRENGTH" PLC
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I've been following it for quite some time. It will definitively be a good option for OpenPLC, even to run the ladder logic embedded.
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It is easy and cheap to expand ESP8266 with analog or digital I/O. There are plenty shields available for very little money all over internet (aliexpress, etc), they all work over I2C interface:
  • Based on ADS1115: 4-channel 16bit AD converter with programmable gain
  • Based on MCP4725: 1-channel 12bit DA converter
  • Based on PCA9685: 16-channel 12bit PWM
  • Based on PCF8574: 8-channel digital I/O
  • Based on PCF8575: 16-channel digital I/O
All shields are compatible with ESP8266 3.3VDC I/O, so no level conversion is required. There are more shields like analog/digital multiplexer, etc. Software support is available on GitHub. Make sure you know unique address of each module type usually preset by manufacturer. Some shield allow to select address, so multiple shields of same kind can be connected to same I2C network.
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