AXIOMATIC AX180800, Руководство пользователя

Страница: 12 / 72

UMAX180800, 20 Thermocouple, 2 RTD, 4 Inputs, 6 Relays Dual CAN Controller Version 1 Page: 12-71
•
MODBUS Messaging on TCP/IP Implementation Guide V1.0b. Modbus Organization. October 24,
2006, 46p.
•
MODBUS Application Protocol Specification V1.1b3. Modbus Organization. April 26, 2012, 50p.
The following Modbus functions are supported by the controller.
Table 3. Modbus Functions Supported by the Controller
Name
Function
Code/Subcode
Description
Read Discrete Inputs 2 Reads values of the universal inputs when they are
in the discrete voltage level mode
Read Input Registers 4 Reads values of the universal inputs
Read Holding Registers 3 Reads one or several configuration parameters
Write Single Register 6 Writes a configuration parameter
Write Multiple Registers 16 Writes one or several configuration parameters
Read/Write Multiple
Registers 23 Writes and then reads configuration parameters
Encapsulated Interface
Transport 43/14 Reads Device Identification
The Modbus addresses are presented in the
Error! Reference source not found. section.
The Unit Identifier in the Modbus TCP header is ignored.
Floating-point variables are presented in a standard IEEE 754 single-precision 32-bit format,
most significant word first. Double-word 32-bit integers are also presented with the most
significant word first.
Reading and writing operations on variables occupying more than one word (a 16-bit Modbus
register) are buffered. The buffering is made transparent to the user. However, it should be
taken into consideration that writing to a non-volatile memory is not performed until all registers
assigned to the variable are written. The writing operation should be performed without
overlapping (writing to the same register twice) and without breaking the writing operation
sequence with a reading operation or a writing operation to a different variable.
The
Modbus functions “Write Multiple Registers” and “Read/Write Multiple Registers”, when
they include all registers assigned to a variable in one function call, meet the abovementioned
writing requirements.
The Modbus writing operations are subject to a validity check. If a configuration parameter
value is not in a valid range, the Modbus operation will succeed, but the configuration
parameter will not be written.
The following device identification information can be read using the Encapsulated Interface
Transport 43/14 function.
Table 4. Modbus Device Identification
Object ID Object Name Description
0x00 VendorName
“Axiomatic”