Modbus Class Summary

The Modbus Class in GPL supports master access to MODBUS/TCP slave devices connected to the local Ethernet network. MODBUS/TCP is an "open" de facto standard protocol that is widely used in the industrial manufacturing environment to communicate between intelligent devices. It has been implemented by hundreds of vendors on thousands of different products to communicate digital and analog I/O and register data between devices.

Table 19-66 briefly summarizes the properties and methods for this Class, which are described in greater detail in the following sections.

Table 19-66: Modbus Class Summary
Modbus Class Member	Type	Description
New Modbus	Constructor Method	Creates an object for a MODBUS connection and specifies the IP address.
modbus_obj.Close	Method	Closes any connections associated with this object.
modbus_obj.ReadCoils	Method	Reads one or more outputs.
modbus_obj.ReadDeviceId	Method	Reads the device ID strings.
modbus_obj.ReadDiscreteInputs	Method	Reads one or more inputs.
modbus_obj.ReadHoldingRegisters	Method	Reads one or more holding registers.
modbus_obj.ReadInputRegisters	Method	Reads one or more input registers.
modbus_obj.Timeout	Get/Set Property	Gets or sets the timeout, in milliseconds, that this connection will wait for a reply before throwing an exception.
modbus_obj.WriteMultipleCoils	Method	Writes multiple outputs.
modbus_obj.WriteMultipleRegisters	Method	Writes multiple holding registers.
modbus_obj.WriteSingleCoil	Method	Writes a single output.
modbus_obj.WriteSingleRegister	Method	Writes a single holding register.