ModbusAsyncDevice

The ModbusAsyncDevice is a component, which is responsible for servicing a physical device connected to the Modbus network. The AAC20 device acts as a Modbus master to all other Modbus devices on the attached RS485 port. Each device is represented by a Modbus device and has a unique Modbus address (1 to 247) as well as other Modbus config data and starting addresses for Modbus data items (coils, inputs, input registers, holding registers). The component has a Ping action available under the right-click, which sends a test message to the device to check the device status. Each ModbusAsyncDevice has a Ping Address container slot with 3 properties slots (Address Format, Ping Address Reg, Ping Type). These properties specify a particular data address (either input register or holding register) to use as the device status test (meaning Monitor ping requests). Ping requests are generated at the network-level by the configurable network monitor (ModbusNetwork -> Ping Enabled). If enabled, a network’s monitor periodically pings (queries) this address. If any response from the device is received, including an exception response, this is considered a proof of communication, and the Modbus client device is no longer considered down if it was previously marked so.

The ModbusAsyncDevice component must be placed under the ModbusAsyncNetwork component.

The ModbusAsyncDevice component has the following slots:

• Status: Device’s actual status (read-only);

  • Available options: OK (device is working properly), Disable (device is disabled, the Enable slot is in false), Down (device is not available), Ok, some points down/error (error in points reading), Network disabled (Modbus network is disabled);

• Fault Cause: fault cause description;

• Fault Status: device error status (true: device communication error);

• Enable: enables/disables the device;

• Device Address: Modbus device physical address;

  • Available options: 0 (network broadcast address), 1-248 (addressing range);

• Timeout: max. device response time from the device request;

• Inter Message Delay: time between messages sent to the device;

• Retry Count: max. number of error messages (CRC error, lost messages);

• Address Format: Modbus address format;

  • Available options: Modbus, decimal;

• Ping Address Reg: input or holding type register’s number, which will be read for device connection test;

• Ping Type: tested register type;

  • Available options: input/holding;

• Byte Order: byte reading order;

  • Available options: for 32-bit: 3210 (Big endian), 1032 (Little endian).