CiDRA Passive Sonar Transmitters - Manual (Page 11)

2
TRANSMITTER MODBUS REGISTER OVERVIEW
2.1 Introduction
The chapter will describe the MODBUS registers available in the
transmitter, and how to read and write them.
Registers are arranged in groups by format (i.e. float, char) to facilitate
reading and writing in blocks, and function (User, Algorithm, Filter
etc.).
Multiple register values (for example, Floating Point values) by default
are arranged to conform to IEEE specifications for Floating Point
numbers. There is an option available through the meter configuration
to swap the two registers for compatibility.
2.2 Making and Saving Changes
In order to change Holding Registers, first write a value of 0x55AA to
Holding Register 4 (the ‘Run Mode’ Register to ‘Write Enabled’).
Changes to any Holding Register(s) can then be made.
In order to validate changes and commit them to FLASH, write a value
of 0xEDF1 (‘Commit Changes’) to the Run Mode register (address 4).
An error will be returned after a Commit if any of the Holding Register
changes are invalid (outside bounds, etc.).
2.3 Passwords
Password functions are available, but by default are disabled. A user
would write their password to the Password Input Holding Register
(Register 0) to set the access level for the session. Sessions timeout
after a configurable number of seconds of no valid reads or writes.
Passwords consist of single register integer values that range from 1
thru 65535 (0xFFFF hex).
All passwords are set to 0, disabling the password feature by default.
Passwords affect Read/Write access to Holding Registers. Input
Registers are always readable.
The three levels of access are:
•
Administrator Ability to set any passwords, as well as read or
write Holding Registers
•
Level 1 Ability to Read or Write any Holding Registers, as well
as setting Level 1 or Level 2 passwords
•
Level 2 Ability to Read Holding Registers, as well as setting
the Level 2 password.
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