Modbus

General modbus

Modbus is a signalling protocol developed in the 1970’s. More information can found at this site here. The protocol allows an application to query a server, and retrieve values and write values. These values represent sensor readings or control set points. But note, the variable names, or units are not provided when querying a Modbus server, only the values.

Ardexa is able to easily read Modbus enabled machines. However, we need the following information to make sure all parameters are known and collected to the cloud: 1. Machine brand and model. This allows us to understand the type of machine being monitored or controlled. 2. Preferred name for machine or controller: This allows us to name the data source correctly. 3. Connection Type: Is the connection made via Ethernet/Wifi, Bluetooth or RS485, or some other protocol?

4. IP Address: The IP address must be a static address. IT MUST NOT be a dynamic address. Provide the static IP address of the Modbus Server and specify the port (if other than the Modbus standard 502 port).

5. RS485: If connecting via RS485, provide the line speed, number of start bits, number of stop bits, number of data bits and address of the Modbus device.

6. Modbus setting: Ensure Modbus is turned on and available for read/write. Most devices do not have Modbus turned on by default. Since Modbus does not have inherent security, make sure the device is not open to the Internet.

7. For each variable available from Modbus, provide the ALL the following information. If this information is available from a manufacturer’s guide, then just send the guide to Ardexa.

1. Register(s) that the value exists. Sometimes 2 registers make 1 variable.

2. Name of the variable (e.g: Grid Voltage)

3. Units of the variable (e.g: Volts)

4. Scale of the variable (e.g: must be divided by 100 to get Volts)

5. Read only or Read/Write. Whether the variable is Read Only (RO) or Read/Write (RW)