Instruction manual

Modbus Implementation Tank Gauge Transmitter

50 Installation and Operations Manual

Note! In all of the following communication examples, the error check value is dependent

upon the mode of transmission.

9.5.1 Integer Data

The integer data is a whole number between 0 and the maximum Modbus integer

(inclusive). The maximum Modbus integer is a user-configurable variable that is a whole

number between 0 and 65,535 (inclusive). The integer data must also be scaled for each

data type by entering the desired units, a minimum, and a maximum value. In order for

the integer value to be correctly interpreted, these scaling factors must match the

format expected by the host system. Scaling of the integer parameters is accomplished

through floating-point registers or by using the Model 1200 Handheld Interface.

The following communication example shows the request for one register starting at

For the following example, assume:

• minimum = 1 meter

• maximum = 15 meters

• maximum Modbus integer = 65,534

Status Bit (L) Low-order data address byte of the first bit to read or write

Error Check Message checksum CRC (Cyclical Redundancy Check)

Term Definition

Host Request

Address Function

Code

Start Reg

# of Reg

Error

Check

01 03 00 00 00 01 XX

ATT Response

Address Function

code

Byte

Count

Data

MSB

Data

LSB

Error

Check

01 03 02 41 24 XX