51. Modbus¶
SolarNode supports Modbus integration through serial port (RTU) and TCP networks.
This integration is provided by the Modbus Communication Support (Nifty Modbus) and Modbus Communication Support - Serial (Nifty Modbus JSC) plugins, which are included in the solarnode-app-io-modbus-nifty-jsc package in SolarNodeOS.
51.1 Use¶
Once installed, new Modbus serial connection and Modbus TCP connection components will appear on the Settings > Components page on your SolarNode. Click on the Manage button to configure networks. You'll need to add one configuration for each Modbus network you want to collect data from.
51.2 Serial (RTU)¶
The Modbus serial connection allows you to connect to Modbus RTU devices on a serial network.
Each configuration contains the following overall settings:
| Setting | Description |
|---|---|
| Service Name | A unique name to identify this network with. Other components will refer to this name to make use of the connection. |
| Serial port | The device port name. This varies by operating system. Some examples are /dev/ttyUSB0 and COM1. |
| Baud | The maximum communication speed to use, for example 9600. |
| Data bits | The number of data bits per message. Must be an integer between 5 and 8. |
| Stop bits | The stop bits value to use. May be one of 1, 2, or 3 (where 3 equals 1.5 stop bits). |
| Parity | The parity to use. May be one of none, even, or odd. |
| Receive timeout | The number of milliseconds to wait for a response. |
| Flow control in | The input flow control to use. May be one of none, xon/xoff in, or rts/cts in. |
| Flow control out | The output flow control to use. May be one of none, xon/xoff out, or rts/cts out. |
| RS-485 Mode. | Toggle RS-485 mode on the serial device. This is not required for all RS-485 networks (USB adapters generally do not require this, for example). When enabled then the other RS-485 settings are activated as well. |
| RS-485 RTS High | Enable to set the RTS line high (to 1) when transmitting. Only applicable when RS-485 Mode is enabled. |
| RS-485 Termination | Toggle RS-485 bus termination. Only applicable when RS-485 Mode is enabled. |
| RS-485 Echo | Enable to enable receive during transmit, typically resulting in transmitted data echoing back as received data. Only applicable when RS-485 Mode is enabled. |
| RS-485 Before Send Delay | A number of microseconds to wait after enabling transmit mode before sending data. Only applicable when RS-485 Mode is enabled. |
| RS-485 After Send Delay | A number of microseconds to wait after sending data before disabling transmit mode. Only applicable when RS-485 Mode is enabled. |
| Port lock timeout | The maximum number of seconds to wait to acquire exclusive use of the configured port. Multiple components can use the same port, but only one at a time. If one component is using the port and another tries to, the second component will wait at most this many seconds for the first component to finish using the port before giving up. |
| Keep Open | The number of seconds to keep the connection open for reuse by multiple Modbus transactions. Set to 0 to open and close the connection for each transaction. |
| Reply Timeout | The maximum amount of time to wait for a Modbus message reply, in milliseconds. |
| Send Delay | A minimum delay to introduce between Modbus messages, in milliseconds. Some devices cannot handle messages at a high rate. Configure a positive integer to force a minimum delay between successive messages. |
| Max Ports | The maximum number of serial ports that can be opened at once, or 0 for no limit. |
| Wire Logging | Toggle wire-level message logging. TRACE level logging must also be enabled for the net.solarnetwork.io.modbus.X log name. |
| CLI Publishing | Toggle command line interface messages to help troubleshoot Modbus issues. |
51.3 TCP¶
The Modbus TCP connection allows you to connect to a Modbus device on a specific IP address (or hostname) and port number using the TCP protocol.
Each configuration contains the following overall settings:
| Setting | Description |
|---|---|
| Service Name | A unique name to identify this network with. Other components will refer to this name to make use of the connection. |
| Host | The host name or IP address to connect to. |
| Port | The port to connect on. |
| Port lock timeout | The maximum number of seconds to wait to acquire exclusive use of the configured port. Multiple components can use the same port, but only one at a time. If one component is using the port and another tries to, the second component will wait at most this many seconds for the first component to finish using the port before giving up. |
| Keep Open | The number of seconds to keep the connection open for reuse by multiple Modbus transactions. Set to 0 to open and close the connection for each transaction. |
| Reply Timeout | The maximum amount of time to wait for a Modbus message reply, in milliseconds. |
| Send Delay | A minimum delay to introduce between Modbus messages, in milliseconds. Some devices cannot handle messages at a high rate. Configure a positive integer to force a minimum delay between successive messages. |
| Max Threads | The maximum number of client network threads to support, or 0 for no limit. For some networks this may limit the number of ports that can be opened. |
| Wire Logging | Toggle wire-level message logging. TRACE level logging must also be enabled for the net.solarnetwork.io.modbus.X log name. |
| CLI Publishing | Toggle command line interface messages to help troubleshoot Modbus issues. |