Figure A.34 - Modbus Connection; A7.2 - Configuration - Ametek OXYvisor Installation, Operation & Maintenance Manual

Installation, Operation & Maintenance Manual
OXYvisor Optical Oxygen Analyzer
The maximum distance of RS-485 without using a repeater is
4000 feet (1220 meters) at baud rates up to 90Kbps. Extend that
distance by adding an RS-485 Repeater or Optically Isolated
Repeater every 4000 feet.
USEFUL INFORMATION

Figure A.34 - Modbus Connection

A7.2 - Configuration

A7.2.1 - Settings
The following setting are used to communicate with the OXYvisor as a Slave Device.
A7.2.2 - Function Codes
The OXYvisor Modbus RTU protocol uses a subset of the standard Modbus RTU function codes to provide
access to process-related information. Several standard function codes are employed and supported, shown
in the table below. These standard function codes provide basic support for IEEE 32-bit floating point numbers
and 16-bit integer register representation of instrument's process data.
Function
Code
03 Read Holding Registers
04 Read Input Registers
06 Write Single Register
16 Write Multiple Registers
Table A.18 - Function Codes for Read / Write Access
Setting
Mode
Baud rate
Data Bits
Stop Bits
Parity
High Byte First
Slave ID
Table A.17 - Configuration Setting
Name
Read Data in 16-bit Register Format (high/low). Used to read integer or floating-point process
data. Registers are consecutive and are imaged from the instrument to the host.
Write Data in 16-bit Integer Format (high/low) ONLY.
Write Data in 16-bit Format (high/low). Used to write integer and floating-point override data.
Registers are consecutive and are imaged from the host to the instrument.
Note: Can write floating point data using this Function Code
RS-485 Master
< 4000 ft (1220 meters)
Data (B) -
Data (A) +
Value
RTU
115200
8
2
None

01, 02, ...
Usage
Terminal
Terminal
75