Model 3095FB Multivariable Transmitter with Modbus Protocol
Modbus Protocol Guide
Page 10 of 79
2.3.1 Register Map (available for 3095FB output board Rev. 107 or later)
There are two base register blocks used in the register map. These register blocks contain the
integer data and the floating point data. To improve connectivity with many different kinds
of hosts, these base register blocks appear in other address ranges, as shown in Figure 2-1 .
2.3.1.1 Accessing Floating Point Registers
The host can access each floating point register in 3 different locations. To access the 16-
bit floating point register pairs in the regions other than the base region, simply add the
base register address (i.e. 401) to the desired range (i.e. 20,000), which gives the new reg-
ister address (i.e. 20,401). The 32-bit floating point numbers do not match up one to one
with the base floating point register pairs, because the 32-bit floating point registers take
half the register space of the 16-bit floating point register pairs. To access the 32-bit float-
ing point registers (7401-7444) use [Equation 1] or see for the complete layout of the 32-
bit register block.
[Equation 1] 32-bit register address = 7401 + (base address - 401) / 2
Examples:
Differential Pressure = 7401 + (401 - 401) / 2 = 7401
Static Pressure = 7401 + (403 - 401) / 2 = 7402
Differential Pressure Damping = 7401 + (441 - 401) / 2 = 7421
For example, the host can read the floating point value for Differential Pressure(DP) from
3 separate register locations. The DP can be read as 16-bit register pairs by reading regis-
ters 401-402 or 20401-20402. The DP can also be read as one 32-bit register at location
7401.
2.3.1.2 Accessing Integer Registers
The integer registers consist of the input registers, holding registers, and ASCII registers.
The host can access each integer register in 5 different locations. To access the 16-bit reg-
isters in the regions other than the base region, simply add the base register address (i.e.
61) to the desired range (i.e. 3,000), which gives the new register address (i.e. 3,061).
For example, the host can read the Static Pressure (SP) Unit Code from 5 separate loca-
tions. The transmitter address can be read from registers 61, 3061, 30061, 40061, or
50061.
