Cameron Scanner 3100, Manual

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Standard Modbus Functions
The Modbus functions supported by the Scanner 3100 are as follows:
Function Code (Hex) Description
03 Read Holding Registers
10 Preset Multiple Registers
Data Types
Various data types are implemented in the Scanner 3100. The following table lists the formats and the numbers of bytes
and registers associated with each type.
Data Format Data Type Byte Count Register Count
16-bit Floating Point (FP) 4 2
Unsigned Long (INT32) 4 2
Packed ASCII (String [4]) 4 2
The word ordering for multiple register data types, such as floating-point numbers or long integers, is for the most signifi-
cant word to appear first in the message.
Packed ASCII
The Packed ASCII (PA) type contains four bytes that are four unsigned characters. Generally, multiple Packed ASCII
types are arranged consecutively for implementing strings. For example, the Model Number is a string of 16 unsigned
characters that is implemented as four Packed ASCII registers. Here is an example of a model number from the 16-bit in-
ternal Modbus map that contains the string “S3100-G1.”
Register Hexadecimal ASCII Characters
1009 53 33 31 30 S310
1011 30 2d 47 31 0-G1
1013 00 00 00 00 <UNUSED>
1015 00 00 00 00 <UNUSED>
Unused characters at the end of each string will report 0x00 hexadecimal.
Registers
Each register has an Access type: read-only or read-write, as described below.
Access Type Description
Read Only (RO) Register Can Only Be Read
Read/Write (RW) Register Can Be Read and Written
The registers are grouped into Modbus map blocks according to function. The Scanner 3100 contains the following map
functions:
Register Sections Starting Address Register Size
Command Registers 71 16-Bit
System Information (General) 1001 16-Bit
System Measurements 1101 16-Bit
Status 1501 16-Bit
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Section 2 Scanner 3100 Modbus Protocol