User`s manual

Chapter 4 Serial Communications AX2200/AX2300 Instruction Manual

4-16 CM2-AX2000-2001 (Rev. 4, 4/2014)

Each range of register numbers maps to a unique range of addresses that are

determined by the function code and the register number. The address is equal to

the least significant four digits of the register number minus one, as shown in the

following table.

Registers Function Codes Data Type and Address Range

00001-09999 01, 05, 15 Read/write bits 0000-9998

10001-19999 02 Read-only bits 0000-9999

30001-39999 03, 04 Read-only 16-bit registers 0000-9998

40001-49999 03, 06, 16 Read/write 16-bit registers 0000-9998

The meter serial number and those variables that are commonly monitored (mass,

volume and energy flow rates, total, pressure, temperature, density, viscosity,

Reynolds number, and diagnostic variables such as frequency, velocity, gain,

amplitude and filter setting) are accessible via the Modbus protocol. Long integer

and floating point numbers are accessed as pairs of 16-bit registers in the register

order selected in the Modbus Order menu. Floating point numbers are formatted

as single precision IEEE 754 floating point values.

The flow rate, temperature, pressure, and density variables may be accessed as

either the flow meter internal base units or in the user-programmed display

units, which is determined by the programming Output Menu’s “Modbus

Units” item. The display units strings may be examined by accessing their

associated registers. Each of these units string registers contain 2 characters of

the string, and the strings may be 2 to 12 characters in length with unused

characters set to zero. Note that the byte order affects the order in which the

strings are transmitted. If the Modbus Order menu (see page 2) is set to 0-1:2-3

or 2-3:0-1, then the characters are transmitted in the correct order; if set to 1-

0:3-2 or 3-2:1-0, then each pair of characters will be transmitted in reverse

order.