Teledyne 9060Z - Zirconium oxide flue gas oxygen analyzer - Manual (Page 61)

Model 9060Z Manual
61
APPENDIX 4, MODBUS™
The Teledyne Analytical Instruments 9060Z transmitter has the ability to work as a Modbus slave node
on serial RS‐232 or 3‐wire RS‐485 via RTU mode transmissions. By accessing information stored in the
input and holding registers it is possible to access runtime variables, alarm conditions and modify the
device configuration.
The implementation of the Modbus protocol is limited to the specific command set relevant to
reading and writing register variables. Attempting to send unrecognised commands will result in
appropriate error responses
MODBUS™ Functions Supported:‐
0x03: Read Holding Registers
0x04: Read Input Registers
0x06: Write Single Holding Register
0x08: (return query data – for loopback testing)
0x10: Write Multiple Holding Registers
0x16: Mask Write Holding Register
0x17: Read/Write Multiple Holding Registers
0x2B: Encapsulated Interface (read device
information)
0x41: Special Instruction Function
Serial Configuration
The serial configuration for the slave device is accessed in the Commissioning menu of the
transmitter. Default settings are highlighted in bold.
Baud Rate 9600, 19200, 38400, 57600
Parity Even, Odd, None
Stop Bits 1
Interface RS‐485, RS‐232
All holding register addresses contain a single 16 bit value, however some variables span multiple
holding registers to yield a single 32 bit variable.
When reading register values be aware that the byte order of data within registers may differ from
that of the target system.
Modbus Protocol
The modbus over serial line protocol defines a messaging system for master/slave communications.
Only one master device may be connected to any network with one or several slave nodes.
In unicast mode, the master initiates communication with a specific slave node by sending a request
message. The slave processes the request and returns a reply message containing the requested
information or a confirmation that the request was fulfilled.
Modbus requests are transmitted as a formed request frame with a CRC for data integrity checking.
The frame for each request and reply type will vary somewhat, but will always have the basic
structure described below:
1 byte 1 byte up to 255 bytes 2 bytes
slave address function code data checksum
Internal Representation of Dates & Alarm Status
The transmitter stores all dates as an unsigned 32bit count of seconds elapsed since 1‐Jan 2004.