ASHP-MIB19N Samsung ASHP Could not connect to Modbus device

Hardware Heatpump
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1

Hi Everyone,

New here and attempting to help out my dad who has had a heat pump installed under the UK Eco Scheme.

He has a 12kW Samsung Gen 6 heat pump installed and I wanted to record its performance data directly from the heat pump as I am not looking for absolute values but the ability to trend the heat pump instrumentation so I can help him optimise his install. I am a chemical engineer but certainly not a hands on control engineer so looking for some help on setting up a Modbus interface from a PI4 installed with the latest EMON SD card and a Modbus RS485 to USB Adaptor from the EMON shop.

I have installed the SAMSUNG-ASHP-MIB19N modbus module in the heat pump:

ModBus INstall
ModBus INstall1920×2560 448 KB

I have used a Cat6 Ethernet cable run to the USB Modbus using two of the wires as you can see in the picture.

EmonPi USB Modbus
EmonPi USB Modbus1920×1179 167 KB

I have added the code to the Emon Config via EMONCMS and ensured there is no conflict of ttyUSB ports.

I get the following message repeatedly:

Blockquote
INFO SAMSUNG-ASHP-MIB19N Connecting to Modbus device=/dev/ttyUSB0 baud=9600 parity=even datatype=int
ERROR SAMSUNG-ASHP-MIB19N Could not connect to Modbus device

Any thoughts on what i am missing maybe i haven’t set something up on the MIB19N interface module or i have wired it incorrectly or ??

Thanks,

Gareth Richardson

2

Hi Gareth,

Have you tried swapping the wires connected to the A and B terminals on your USB interface?
You may (or may not!) need to connect the ground terminal to the Modbus module.

You said you have an MIB19N module, but the only docs I found are for an MIM-B19N.
The circuit board shown in the docs looks like the one in your picture, and if they are indeed
the same product, it looks as if you have the Modbus address set to 1.

The Modbus spec calls for even parity, which the line in the eror message you’re getting
says you’re using. However, it’s not uncommon to see no parity used.

MIM-B19N_Modbus_Interface_Module_GB_EN_221130-D01.pdf (417.5 KB)

3

Hi Bill,

Yes you are correct its not a MIB but MIM a typo on my part, thanks for replying!

I tried that today and to no effect. I then decided to double check the connection to the MIM-B19N unit and found one of the Ethernet connections had come off (probably happened when closed the heat pump up). Reconnecting this cable seemed to still come up with the same error.

I checked the LED lights on the MIM-B19N and the green light is flashing which according to the manual shows it is communicating with the heat pump, see below:

MIM-B19N LED Lights
MIM-B19N LED Lights928×460 34.6 KB

I checked the Config and the address is set to 1 so that seems to be correct.

When I relook at the Error code I wonder if it is the EmonPi not picking up the Modbus USB?

4

Have you tried using no parity vice even parity?

5

Samsung heat pump needs Even parity, see: https://docs.openenergymonitor.org/emonhub/emonhub-interfacers.html#samsung-ashp

Could you post the full emonhub.conf and emonhub.log

Could you SSH into the RasPi and post the output of

/dev/serial/by-id/ -la

This will list all the connected serial ports.

6

Hi Glyn,

Config attached:
Dads EMONPi Config with Modbus.txt (4.9 KB)

I had to change the code slightly:

pi@emonpi:~ $ sudo ls -la /dev/serial/by-id/

total 0

drwxr-xr-x 2 root root 60 Nov 28 21:02 .

drwxr-xr-x 4 root root 80 Nov 28 21:02 ..

lrwxrwxrwx 1 root root 13 Nov 28 21:02 usb-1a86_USB_Single_Serial_586D010779-if00 -> ../../ttyACM0

Thanks for helping learning a lot doing this!

7

Ah looks like your USB modbus device is coming up as /dev/ttyAMA0.

In your Samsung section of your emonhub.conf try changing /dev/ttyUSB0 to /dev/ttyAMA0.

I’m assuming you only have one USB device attached to the emonPi?

If you have any further issues, could you post a copy of your emonhub.log?

8

So made some progress, see attached log file seems to be talking to heat pump but not reading the registers. I managed to figure out the Modbus location was 0 not 1 which seemed to get it working but not sure what next.
log file .pdf (228.5 KB)

9

Hi Gareth, did you get this resolved, i am having very similar issues with only the green Led flashing. Thanks

10

Great, that’s good progress. Can you share your emonhub.config? The Samsung section should look like this:

[[SAMSUNG-ASHP-MIB19N]]
    Type = EmonHubMinimalModbusInterfacer
    [[[init_settings]]]
        device = /dev/ttyAMA0
        baud = 9600
        parity = even
        datatype = int
    [[[runtimesettings]]]
        pubchannels = ToEmonCMS,
        read_interval = 20
        nodename = samsung-ashp
        # prefix = sdm_
        [[[[meters]]]]
            [[[[[ashp]]]]]
                device_type = samsung
                address = 0
                registers = 75,74,72,65,66,68,52,59,58,2,79,87,5,89
                names = dhw_temp,dhw_target,dhw_status,return_temp,flow_temp,flow_target,heating_status,indoor_temp,indoor_target, defrost_status,away_status,flow_rate,outdoor_temp,3_way_valve
                scales = 0.1,0.1,1,0.1,0.1,0.1,1,0.1,0.1,1,1,0.1,0.1,1
                precision = 2,2,1,2,2,2,1,2,2,1,1,2,2,1

I’m a bit confused when you said the Ethernet connections had come off? The MIM-B19N does not have any Etherent connections. It looks like this:

samsung-air-conditioning-mim-b19n-modbus-interface-module-for-building-management-syste-19057-p
samsung-air-conditioning-mim-b19n-modbus-interface-module-for-building-management-syste-19057-p1200×1200 262 KB

Can you share a photo of your MIM-B19N showing the connections and the position of the rotary ID selector?