Modbus Rtu Instructions (Dl260); Modbus Read From Network (Mrx) - Automationdirect.com DirectLOGIC DL205 Series User Manual

Modbus RTU Instructions (DL260)

Modbus Read from Network (MRX)

The Modbus Read from Network (MRX) instruction is used by the DL260 network master
230
to read a block of data from a connected slave device and to write the data into V–memory
addresses within the master. The instruction allows the user to specify the Modbus Function
240
Code, slave station address, starting master and slave memory addresses, number of elements
250-1
to transfer, Modbus data format and the Exception Response Buffer.
260
DS Used
HPP N/A
• Port Number: must be DL260 Port 2 (K2)
• Slave Address: specify a slave station address (1 to 247)
• Function Code: The following Modbus function codes are supported by the MRX instruction:
01 – Read a group of coils
02 – Read a group of inputs
03 – Read holding registers
04 – Read input registers
07 – Read Exception status
• Start Slave Memory Address: specifies the starting slave memory address of the data to be read. See
the table on the following page.
• Start Master Memory Address: specifies the starting memory address in the master where the data
will be placed. See the table on the following page.
• Number of Elements: specifies how many coils, inputs, holding registers or input registers will be
read. See the table on the following page.
• Modbus Data Format: specifies Modbus 584/984 or 484 data format to be used
Chapter 5: Standard RLL Instructions - Modbus
DL205 User Manual, 4th Edition, Rev. B
1
2
3
4
5
6
7
8
9
10
11
12
13
14
A
B
C
D
5–205