Modbus Node

A serial communication protocol often used in industrial and automation systems. Modbus can be used to send data from Rayven to PLCs or other industrial devices, enabling integration with industrial control systems and equipment for monitoring.

Modbus is a commonly available means of connecting industrial electronic devices in industrial environments.

It uses character serial communication lines, Ethernet, or the IP suite as a transport layer. Modbus supports communication between multiple devices connected to the same cable or network and is often used to connect a plant supervisory computer with a remote terminal unit (RTU) in supervisory control and data acquisition (SCADA) systems.

A single physical output is called a coil, and a single physical input is called a discrete input or a contact and the data types are:

Object type	Access	Size	Address Space
Coil	Read-write	1 bit	0x0000 – 0xFFFF
Discrete input	Read-only	1 bit	0x0000 – 0xFFFF
Input register	Read-only	16 bits	0x0000 – 0xFFFF
Holding register	Read-write	16 bits	0x0000 – 0xFFFF

Only coils and holding registers can receive input. Note, too, the sizes of these registers - coils are limited to 1 bit, and holding registers to 16 bits.

Functionality

The Modbus node will send data to the designated field addresses for the specified device.

How to Use

Implementation

In the Rayven Workflow Builder:

Select Outputs.
Drag the Modbus node to the canvas.
Double click on the Modbus node to open the configuration window.

Configuration

Section: General
This section contains basic configuration elements required for any Modbus implementation.
Field	Requirement	Comments
Node Name	Mandatory	Enter a name for this node. This provides a handle to which you and others can refer, so it should be simple but meaningful and explain the node’s purpose.
Address	Mandatory	Enter the destination IP address of the Modbus device.
Port	Mandatory	Enter the port for the Modbus PLC. Note that the node defaults to 502, which is the Modbus default port.
Field Name	Mandatory	A reference name for the row to enable the user to easily manage the list of outputs. It serves no functional purpose.
Outputs	Mandatory	Select a Modbus Outputs type from the dropdown menu: Coil Outputs: These are writable coil addresses that take a boolean. Register Outputs: These are writable holding registers that take a ushort.
Address	Mandatory	Enter Modbus field address (e.g. 40001 - 49999) obtained from the Modbus configuration. Note that, since Modbus has a field size limited to 1 bit or 16 bits, flow variables must first be transformed to the appropriate data-type and may need to be sent to multiple addresses.
Value	Mandatory	Enter the json field that will be the data source.

Activation

Once configured, click the 'Activate' button and then click 'Save'.