Offshore 5801 User manual - page 7
5 of 13
2.4 UNIT SWITCH SETTINGS
During initial installation, the unit needs to be opened and switches set to match the units
interface connection.
If the unit is to be used with a fixed source address style CAN bus interface, then the fixed
address mode switch needs to be set to the ON position and the fixed source address set in
the Hi and Lo order rotary switches. If the unit is to be used as an NMEA2000® sensor then the
Device Instance should be set in the two small rotary switches. These would normally both be
set to “0”
Modbus
It is possible to select Modbus baud rate and parity using SW1 ; please refer to the table 1
below. Note: Modbus is only available in NMEA2000
® mode.
The 5801 MODBUS frame consists of 8 data bits, 1 parity bit, and 1 stop bit. Please refer to
Modbus specification for further information.
Modbus Commands
The 5801 Trim Tab Adaptor identifies as slave 48 (0x30) and supports one command (0x3) [Read
Holding Registers].
Any request for registers not implemented will result in error code (0x2) [Illegal Address] to be
returned.
Any request for a command that is not implemented will result in error code (0x1) [Illegal
Instruction] to be returned.
Please refer to table 2 for memory locations.
Recommended Usage
We recommend that the device is polled at a maximum of once per second. Ideally this request
should handle all 3 registers; however, the ability to poll individual registers is implemented as
per MODBUS specification.
SW1
Baud Rate
Parity
0
9600
Even
1
9600
Odd
2
19200
Even
3
19200
Odd
4
38400
Even
5
38400
Odd
6-F
9600
Even
Memory
Location
Address H
Address L
Data H
Data L
40000
00
00
00
Port Tab Pos
40001
00
01
00
Stbd Tab Pos
40002
00
02
00
Cent Tab Pos