Reference — Frigomar gateway

The MUXEN devices this gateway publishes

Device	Function	Instance	What it carries
HVAC, serial channel 1	21	configured (InstanceNum), default 0	the air conditioner on serial 1
HVAC, serial channel 2	21	configured (InstanceNum), default 1	the air conditioner on serial 2
HVAC, serial channel 3	21	configured (InstanceNum), default 2	the air conditioner on serial 3
HVAC, serial channel 4	21	configured (InstanceNum), default 3	the air conditioner on serial 4
Generic I/O	17	configured (InstanceNum), default 255	the box's own relay and analog input

The instance is chosen per channel, by writing that channel's InstanceNum and restarting. The four channels have separate settings; the serial connector a unit is plugged into is what decides which of the four it is. A channel whose InstanceNum has never been written falls back to its channel number — 0 for serial 1, 3 for serial 4.

MQTT topics on the Brain follow device/<function>/<instance>/<frame>, so a unit left on its default instance is device/21/0/life.

What it publishes

device/21/<instance>/life, about once a second, only while the unit answers:

Field	Meaning
realTemp	the temperature the unit measures, in whole °C
tempSetPoint	the set point the unit is holding, in whole °C
currentMode, currentModeCode	0 heating 1 cooling 2 dehumidify 3 auto 4 fan only
fanSpeed, fanSpeedCode	0 auto 1 minimum 2 medium 3 maximum
runningMode, runningModeCode	0 off 1 on
BindToParc	the battery park this unit is counted in
counter	a rolling counter, to tell a fresh message from a repeat

Tenths of a degree are dropped: the unit reports 0.1 °C, the MUXEN bus carries whole degrees.

device/17/<instance>/life, when the generic I/O is addressed and EnGenIo is 1: every 500 ms and on change.

Field	Meaning
relay0	the box's relay
ana0	the box's analog input, in millivolts
input0, input1, relay1, ana1	always 0 — this box has no second relay, no dry-contact inputs and no second analog input

Commands

Published to device/21/<instance>/command:

Payload	Effect
{"command":0,"parameter":0}	switch off, and hold the unit in forced mode
{"command":0,"parameter":1}	switch on, and hold the unit in forced mode
{"command":0,"parameter":2}	back to automatic — battery protection and wall switch active again
{"command":1,"parameter":<18…30>}	write the temperature set point, in °C

Anything else is discarded. A set point below 18 or above 30 is discarded. Nothing is written to a unit that is not answering, and nothing is queued or retried.

Operating mode, fan speed and the panel settings are read only — this gateway never writes them.

The generic I/O relay is commanded on device/17/<instance>/command with {"channel":0,"requestOn":true} / {"channel":0,"requestOff":true}.

Automatic running control

Active only while the unit is in automatic mode — that is, until the first forced on/off command, and again after a restart of the gateway.

The battery park reports	The gateway
healthy, state of charge ≥ MinSocToWork	leaves the unit alone, and toggles it on each rising edge of RemoteCmdEqn
healthy, state of charge < MinSocToWork	switches the unit off
overload, low battery, or no battery publishing	switches the unit off

It never switches a unit back on by itself.

The park is BindToParc. 255 means standalone: no park is watched, a permanently healthy battery is assumed, and the protection therefore never acts. An air conditioner cannot detect its park on its own, so the gateway writes 255 at its first start and keeps it until an installer writes a real park number.

Parameters — HVAC (function 21), per channel

Parameter	Type	Default	Meaning
InstanceNum	0…62	255, read back as the channel number	this channel's instance. Unlike most devices of this family a fresh channel publishes immediately, as 0, 1, 2 or 3
BindToParc	park number, or 255	254 → rewritten to 255 at the first start	the battery park whose state gates the unit. 255 — standalone, protection disabled
MinSocToWork	%	20	below this state of charge the unit is switched off
RemoteAddr	Modbus address	1	the Modbus address of the unit on this channel
RemoteCmdEqn	text, up to 255 characters	empty	logic expression whose rising edge toggles the unit — see below
MinSetPoint, MaxSetPoint	°C	18, 30	not applied by this version — the accepted range is fixed at 18…30 °C
ProductId, HardwareId, SoftwareId, SoftwareVersion	read-only		see Reference

Changes take effect at the next restart — write with --reboot. One restart restarts all four channels.

Parameters of the generic I/O device are the ones common to every box of this family: Reference. EnAnalogPwr is not honoured by this version: the sensor supply follows the hardware, not the parameter.

Routines

Routine	Effect
1	factory reset — 0001 restores the instance number to its default, any higher bit the other parameters
2	locate — the system LED blinks fast for about four seconds. muxen-uds … locate

The wall-switch expression

RemoteCmdEqn is a logic expression over signals seen on the MUXEN bus. It is evaluated whenever one of those signals changes; each time the result goes from false to true, that unit toggles on/off.

Operators: & (and), | (or), ! in front of a signal (not).

Instance numbers inside an expression are written one higher than the device's instance number — the switch published as instance 3 is written 4.

Signal	Written	Meaning
Scheiber switch	SFSP(inst,btn)	button 1…8
8-button panel	F8T(inst,btn)	button 1…8
Keypad	BLK(inst,btn,ctrl,color)	button 1…12
Bloc 8	B8S(inst,type,id,set,reset)	O output 1…8, I dry input 1…6, V analog input 1…3 in mV, C output current 1…8 in 0.1 A
Generic I/O	GIO(inst,type,id,set,reset)	I dry input, V analog input in mV, R relay — id 1…2
Lighting module	ECL(inst,output)	output 1…6
Battery	BAT(inst,type,set,reset)	V 0.1 V, I 0.1 A, T °C, L state of charge %
Interconnect	INT(inst,type,id,set,reset)	I charge input state 1…4, M measurement 1…8
Air conditioner	HVAC(inst)	running or not
Degraded mode	DEG(inst,level)	level 1…15

set and reset are the two thresholds of an analog signal and give it its hysteresis; they are written as 0 for on/off signals.

Example — button 1 of Scheiber switch 4, but only while the lighting output is off:

SFSP(4,1)&!ECL(2,1)

Timings

Channels polled	in turn, one every 125 ms
HVAC life published, per unit	about every 1 s
Modbus reply timeout	500 ms — a silent channel slows the whole cycle
Generic I/O published every	500 ms, and on change
Alarms published every	1 s
Alarms carried at once	32
Reading expires on the Brain after	30 s

The Frigomar side

Link	RS-485, 2-wire half-duplex, line termination switched on by the firmware
Protocol	Modbus RTU, gateway as client
Serial format	9600 baud, 8 data bits, no parity, 1 stop bit — fixed by the firmware
Address	one per channel, RemoteAddr, default 1. The gateway never searches the line
Read	holding registers 1 to 14, in one transaction
Written	register 7 (running mode) and register 2 (temperature set point), one register at a time

Register	What it is	Used
1	measured temperature, 0.1 °C	published
2	temperature set point, 0.1 °C	published, and written
3	panel backlight time	read, not used
4	Celsius / Fahrenheit	read, not used
5	the unit's Modbus address	read, not used
6	sensor offset	read, not used
7	running mode	published, and written
8	fan speed	published
9	load defaults	read, not used
10	mode selection	published
11	sensor selection	read, not used
12	frequency-limitation word	turned into alarms
13	fault code	turned into alarms
14	alarm word	turned into alarms

Alarms

The gateway raises MUXEN alarms on function 21, on the instance of the unit concerned. Codes 0 to 17 are warnings, 18 to 27 are alarms.

From the frequency-limitation word (register 12) — each bit raises and clears its own alarm:

Code	Alarm
0	Phase Current limitation
1	AC Current Limitation
2	Total Power Limitation
3	Power Factor Corrector failed

From the fault code (register 13) — one value at a time:

Unit reports	Code	Alarm
1	4	DC Voltage Overtop
2	5	DC Voltage Low
3	6	AC Current Overtop
4	7	Synch Loss
5	8	Phase Lack detected by speed
6	9	Phase Lack detected by current
7	10	IPM FO falling edge
8	11	IPM FO level
12	12	PFC Current Overtop
13	13	Total Power Overtop
15	14	AD Offset Abnormal
23	15	EEPROM driving failure
25	16	EEPROM control failure
26	17	IPM abnormal temperature

These clear only when the unit reports no fault at all. A unit that moves from one fault to another shows both until it settles.

From the alarm word (register 14) — each bit raises and clears its own alarm:

Code	Alarm
18	Room temperature sensor failed
19	Indoor coil temperature sensor failed
20	Outdoor temperature sensor failed
21	Outdoor coil temperature sensor failed
22	Indoor DC fan failure
23	Compressor discharge temperature sensor failure
24	Low outdoor coil temperature in heating mode
25	Low pressure
26	High pressure
27	Communication error inside the unit

Alarms are refreshed only when the unit answers: they stay as they were while it is silent.

Known limitations

• Operating mode and fan speed are read but never written.
• The set point range is fixed at 18…30 °C; MinSetPoint and MaxSetPoint have no effect.
• EnAnalogPwr has no effect on this box.
• The fault code clears only on "no fault" — see above.
• Sub-zero measured temperatures are not published correctly.
• A forced on/off command disables the battery protection until an auto command or a restart.

Versions

Hardware	Version	Image
CAN/Modbus (990010053)	5.9	010010019-MODBUS-app_frigomar-firmware.srec
CAN/Serial v2 (990010063)	6.4	010010019-SERIAL-V2-app_frigomar-firmware.srec