3 supported modbus function codes – Banner SureCross DX80 Wireless Networks User Manual

Page 7

Advertising
background image

In this format, users can read a 16-bit holding register for all devices or write to a register for all devices using one

Modbus message. Using these registers is the most efficient way to read all status registers, read all analog inputs, or

write all analog outputs.

The following registers contain analog I/O values for the Gateway and all Nodes. Values are stored first for the Gateway,

then for each Node in order of Node address.

Inputs

Outputs

Modbus Register

Address (Decimal)

Description (Inputs)

Modbus Register

Address (Decimal)

Description (Outputs)

6801

Input 1 for Gateway

8001

Output 1 for Gateway

6802

Input 1 for Node 1

8002

Output 1 for Node 1

6803

Input 1 for Node 2

8003

Output 1 for Node 2

...

...

...

...

6951

Input 2 for Gateway

8151

Output 2 for Gateway

6952

Input 2 for Node 1

8152

Output 2 for Node 1

6953

Input 2 for Node 2

8153

Output 2 for Node 2

...

...

...

...

7101

Input 3 for Gateway

8301

Output 3 for Gateway

7102

Input 3 for Node 1

8302

Output 3 for Node 1

7103

Input 3 for Node 2

8303

Output 3 for Node 2

...

...

...

...

7851

Input 8 (Status Register) for

Gateway

9051

Output 8 for Gateway

7852

Input 8 (Status Register) for Node

1

9052

Output 8 for Node 1

7853

Input 8 (Status Register) for Node

2

9053

Output 8 for Node 2

...

...

...

...

For example, 6801 contains the input 1 value for the Gateway, 6802 contains the input 1 value for Node 1, and 6848

contains the input 1 value for Node 47.

2.3 Supported Modbus Function Codes

The supported Modbus function codes are 3 (read multiple), 6 (write single), and 16 (write multiple).

All DX80 Modbus registers are defined as ‘holding registers’ in the 4xxxx address space. Some older PLCs use the register

number space of 4xxxx to imply function code 3 for holding registers. For these systems, add 40000 to our register

number and the PLC software uses the correct function code 3 to access our registers.

The supported Modbus function codes are defined below. For more information about Modbus, see

www.modbus.org

.

Function

Description

3

Reads the contents of a contiguous block of holding registers in a remote device. The request specifies the

starting register address and the number of registers.

6

Writes a single holding register in a remote device. The request specifies the address of the register to be

written and the single register of data.

16

Writes a block of contiguous holding registers in a remote device. The requested written values are specified

in the request data field.

Host Controller Systems

7

Advertising