I received my EW11 about a week ago and have been trying to get it working, but so far without any success.
I’m fairly certain that the wires labeled A and B are not the Modbus connection, but are only powering the display. I measure a constant ~10 V AC on those terminals.
When I connect P and Q to the A and B terminals of the EW11, nothing happens when I try to scan for registers (using your Python script). I also tried swapping the wires, but unfortunately that didn’t change anything.
When measuring the voltage between the P and Q terminals, I see it jump to about 3 V and then drop back to zero after a few seconds. This cycle repeats roughly every 5 seconds. When I measure between P and E (yellow wire), or Q and E, I get about half that voltage. Because of this, I’m fairly confident that the yellow wire (E) is ground.
I checked my schematic and CN21 is not shown there. However, it does appear to exist on my PCB, just without a connector soldered onto it.
Do you think the PQE connection going to the display is the same as the missing CN21 connector? It seems like a big coincidence that PQE would be labeled in the schematic as going to the display, yet not be the Modbus connection.
Do you have any ideas on how I could move forward from here? I really want to get this working, and any help would be greatly appreciated.
My Claude investigation says the PQE connector should be the proper modbus connection but is often unpopulated on the pcb.
The connection to the screen is different.
Presumably you don’t have enough hands to reliably hold wires on there for testing so it looks like you might need a soldering iron too
regarding the PCB picture: you would have to mount both, CN21 and IC6. IC6 is obviously something like the good old MAX485, but as we don’t know if the supply voltage is 3.3V or 5V, you better use something like an SN65HVD1780P. All the rest seems there. Soldering will be no fun as there is coating on the board… Keep us tuned!
I totally missed the of below the CN … And having taken a closer look at my own photo, it looks like IC1 is connected to IC6 as well. Should i solder a chip there as well and which one?
Fix: WiFi temperature control for the Midea 170L heat-pump water heater (Trade Depot / Chromagen / Ecospring, RSJRAC07) in Home Assistant
TL;DR: If you have this heat-pump hot water cylinder and the midea_ac_lan integration can read temps but can't set the temperature (or setting it makes the setpoint go to 0 / the unit play up until you power-cycle it), it's a fixable bug in the Midea library. he real fix is in the midea-local library (a bug report + patch has been filed upstream — link once posted). Until it's released, you can patch it locally:
In midealocal/devices/cd/message.py, the MessageSet._body needs to return the full 25-byte body (power at byte 2, mode at 3, target temp raw at byte 4, and importantly the max-temp at byte 23 must be the device's real max, not 0 — sending 0 there clamps your setpoint).
Re-enable writes on the water-heater entity if a previous workaround disabled them.
Hello - I am from Adelaide. I have the same Chromagent Heatpump. I have configured my EE11 and is now seen in my home assistant intance. This is powered by a POE switch then I used a POE splitter to power this EE11A.
I am in the last part of tapping the A and B of this EE11A.
I took a photo and was trying to compare it with your screenshot. I have noticed yours have less wires. This wires that I have marked are the A and B?
