Reference — MDV battery switch module

The MUXEN devices this module publishes

Device	Function	Instance comes from
Remote battery switch	25	InstanceNum of that device, written by hand. 255 out of the box, and nothing is published until it is set
Battery	5	InstanceNum of that device. Forced to 0 at startup if it has never been set

MQTT topics on the Brain follow device/<function>/<instance>/<frame>, so device/25/0/life is the switch and device/5/0/life the battery.

What the switch frame carries

Switch position	closed or open, taken from the feedback contact
Bus power state	whether the module is currently injecting onto the MUXEN bus
Supply state	whether the module's own power input is good
Injected current	what the module is putting onto the bus and the auxiliary output, in 0.1 A
Boat power-up flag	set for OnOffPulseLength after the switch closes
Boat power-down flag	set for OnOffPulseLength after the switch opens

What the battery publishes

Voltage, current, temperature and state of charge, read from the Hella IBS; the parc it is bound to; and a charge request derived from the voltage against AlertVmin / AlertVmax and their hysteresis. Alongside it, the charge and discharge limits — which the sensor does not know, so they are the four values written in the battery's own configuration.

The battery is published only while the module is powering the bus.

Commanding it

From the Brain, on device/25/<instance>/command:

mosquitto_pub -h 127.0.0.1 -t 'device/25/0/command' -m '{"relay": true}'
mosquitto_pub -h 127.0.0.1 -t 'device/25/0/command' -m '{"relay": false}'
mosquitto_pub -h 127.0.0.1 -t 'device/25/0/command' -m '{"relay": "auto"}'

Field	Values
relay	true — close the main switch false — open it "auto" — release the force and leave the module to its own logic
injection	true — force bus power on false — force it off "auto" — release the force

A command carrying both "on" and "off" at once is refused and both are cleared.

Forcing the injection overrides the whole power-injection logic, including the shutdown delay and the sleep. It is a bench and troubleshooting tool, not a way to configure the boat.

Parameters

Every device carries the four read-only identifiers common to all can-mdv boxes (Reference). Values below are defaults.

Remote battery switch — function 25

Parameter	Default	Meaning
InstanceNum	255	255 means not addressed
EnablePowerInjection	1	0 — the module never powers the MUXEN bus, and publishes no battery 1 — the bus is powered while the main switch is closed
PowerInjectionOffDelay	600000	ms the bus stays powered after the main switch opens, before the module cuts it and sleeps
OnOffPulseLength	2000	ms the boat power-up / power-down flags stay set after the switch moves
RemoteSwitchTimeout	300000	ms the module will drive a coil waiting for the feedback contact before giving up
ReverseSwitchDrive	0	0 — relay 1 opens, relay 2 closes 1 — the two are swapped
IMeaCoef	291	scaling of the injected-current measurement
BatteryIbsType	1	0 — Hella IBS 12 V 1 — Hella IBS 24 V. Read once, at startup
RemoteSwitchEqn	empty	logic equation; every rising edge of its result toggles the main switch. Read once, at startup. Up to 255 characters

Battery — function 5

Parameter	Default	Meaning
InstanceNum	0	set to 0 by the module if it has never been addressed
BindToParc	auto	which battery parc this bank belongs to; decided from the first valid voltage and then frozen
AlertVmin / AlertVminHyst	240 / 5	low-voltage threshold and its hysteresis, in 0.1 V
AlertVmax / AlertVmaxHyst	285 / 5	high-voltage threshold and its hysteresis, in 0.1 V
VChargeMax	285	maximum charge voltage published with the battery, in 0.1 V
VDischMax	240	minimum discharge voltage, in 0.1 V
IChargeMax	500	maximum charge current, in 0.1 A
IDischMax	500	maximum discharge current, in 0.1 A

The battery group carries a few further parameters shared with every MUXEN battery device; this firmware uses only the ones listed above.

Automatic parc detection

Applied once, to the first valid voltage read from the sensor, then written to flash.

Measured voltage	Parc
43.0 – 60.0 V	1
10.0 – 16.0 V	2
20.0 – 30.0 V	3
anything else	standalone

The equation

RemoteSwitchEqn is a logic expression over signals read from the MUXEN bus, in the same syntax used by the relay equations of other MUXEN devices.

Operator	Meaning
&	and
|	or
!	not
^	exclusive or
#	latch
[ ]	sub-expression

A signal is written as its type followed by its parameters in parentheses — B8S(3,I,1,0,0) is dry-contact input 1 of Bloc 8 number 3. Every rising edge of the whole expression toggles the main switch; the level itself does nothing.

Routines

Routine	Effect
1	restore defaults — payload bit 0 restores the instance number, any higher bit restores everything else

The locate routine is not implemented on this firmware: muxen-uds locate is refused.

Timings

Switch frame published every	500 ms, and immediately on any change
Battery published every	1 s
Battery sensor polled every	500 ms
Feedback contact confirmed after	2 s of a steady new position
Bus power held after the switch opens	PowerInjectionOffDelay, 10 min by default
Module goes to sleep after the bus power is cut	5 s
Coil drive gives up after	RemoteSwitchTimeout, 5 min by default
System LED	one blink per second while awake, off while asleep

Limits

Main switches driven	1
Battery sensors read	1
MUXEN instances	0 – 62
LIN speed	19 200 bit/s, fixed
MUXEN bus speed	500 kbit/s

Known limitations

• The battery sensor type and the equation are read only at startup; a power cycle is needed after changing either.
• Instance numbers take effect for published frames immediately, but for commands and for the diagnostic session only after a power cycle.
• With EnablePowerInjection at 0 the module drives the switch but publishes no battery.

Versions

Hardware	Version	Image
can-mdv v2	6.2	010010029-V2-app_mdv-firmware.srec