Network Modbus Rtu Master Operation (Dl260 Only); Modbus Function Codes Supported - Automationdirect.com DirectLOGIC DL205 Series User Manual

Network Modbus RTU Master Operation (DL260 only)

This section describes how the DL260 can communicate on a Modbus RTU network as a
230
master using the MRX and MWX read/write instructions. These instructions allow you to
240 enter native Modbus addressing in your ladder logic program with no need to perform octal
to decimal conversions. Modbus is a single master/multiple slave network. The master is the
250-1
only member of the network that can initiate requests on the network. This section teaches
260
you how to design the required ladder logic for network master operation.

Modbus Function Codes Supported

The Modbus function code determines whether the access is a read or a write, and whether to
access a single data point or a group of them. The DL260 supports the Modbus function
codes described below.
Modbus Function Code
01
02
05
15
03, 04
06
07
08
16
Chapter 4: System Design and Configuration
Master
Slave #1
Modbus RTU Protocol
Function
Read a group of coils
Read a group of inputs
Set / Reset a single coil (slave only)
Set / Reset a group of coils
Read a value from one or more registers
Write a value into a single register (slave only)
Read Exception Status
Diagnostics
Write a value into a group of registers
DL205 User Manual, 4th Edition, Rev. B
Slave #2
DL205 Data Types Available
Y, C, T, CT
Y, C, T, CT
Y, C, T, CT
1
2
3
4
5
6
Slave #3
7
8
9
10
11
12
13
X, SP
14
V
V
A
V
V
B
V
C
D
4–45