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Genvex heat recovery unit

Valid for units compatible with the Optima 251 control panel (ECO 190, ECO 375)

The Genvex unit has two means of communication:

1. Modbus interface located on the control panel

This solution is most suitable if you already have an industry standard modbus interface, that you want to use, while keeping the Optima 251 control panel operational.

(Don't forget the 150 Ohm pull-up resistor between C3 and C4)

2. USB -> Modbus interface located on the control panel

This is the easy solution, if you have the modbus software, but not the appropriate hardware adapter for modbus.

Both interfaces use the Modbus protocol over serial lines [1] The specific implementation is described by genvex her: [2]


3. Serial/TTL lines directly to the unit

This is the solution if you don't want to have the Optima control panel connected.

To make SmartCore take full control of the Genvex unit, the Optima control panel must be disconnected. (Alternatively the SmartCore can listen to the communication with the panel and extract relevant data. But they probably shouldn't both talk to the unit on the same lines)

On the raspberry you can use the serial port at

  • pin 8: TX BCM 14 (UART Transmit)
  • pin 10: RX BCM 15 (UART Receive)
  • pin 6: Gnd


Setting it up

1. OS preparations

Disable console using the serial port, by changing the /boot/cmdline.txt file

at default it looks something like this:

 dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait

Remove the highlighted part:

 sudo nano /boot/cmdline.txt  

The changes will take effect after next reboot.

SmartCore setup