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The 3155 unit supports up to 8 banks each of 28 switches as grouped by the NMEA2000
standard.
Each switch is accessible as either 224 (8 x 28) individual switches or grouped together in 8
Holding Registers designated as Instance 0 to Instance 7.
Note that the NMEA2000 standard assigns 2 bits to each switch with the following values which
vary whether the switch is being read or set:
When controlling or reading the switchves using the Holding Registers then these values MUST
be used by the Modbus Master device.
Please note that these registers are read using command code 4 and written using
command code 16. (decimal)
7.20
Switch Bank Status and Control Registers
Bit Values
Controlling the Switch
Reading the Switch Status
0x00
Turn OFF
Off
0x01
Turn ON
On
0x10
Reserved/No Action
Error
0x11
No Action
Unavailable/Unknown
