1. Field
The teachings in accordance with the exemplary embodiments of this present disclosure generally relate to a method for sharing input and output ports, and more particularly to a method for sharing input and output ports configured for use in an inverter driving a motor.
2. Background
Generally, an inverter for driving a motor is mounted with a variety of input and output ports including digital input (DI), a digital output (DO), an analogue input (AI), and an analogue output (AO). FIG. 1 illustrates input/output ports of an inverter according to prior art.
Referring to FIG. 1, an inverter (100) includes D11 to D17 ports (110), a DO1 port (111) which is a transistor output, a DO2 port (112) which is a relay output, an AI1 port (113) which is a voltage input, an AI2 port (114) which is a current input, an AO1 port (115) which is a voltage output, and an AO2 port (116) which is a current output. In addition, the inverter (100) includes an interface unit (120) for communication with an outside device.
The input/output ports are used for feedback of various sensors (pressure, position, contact point, temperature, flow speed and flux, etc) for each device or an output of a meter, and the number of required input/output ports and types of required input/output ports vary per inverter even in a system. Furthermore, each inverter has a variety of parameters (e.g., analogue scale, offset value, etc) of input/output ports, and is set up to cater to the system.
FIG. 2 illustrates a system using two inverters according to prior art. Referring to FIG. 2, the system using two inverters according to the prior art includes first and second inverters (200, 300), an upper level controller (400) and a sensor (500). In the abovementioned system, the first inverter (200) receives a signal from the sensor (500), the upper level controller (400) and the second inverter (300) through an AI port (211), a DI port (212) and AI port (213).
Meanwhile, in a case there is a need of inputting another signal to the first inverter (200) from the sensor (500), an extension input module (230) was conventionally mounted. However, there is a disadvantage in that addition of the extension input module (230) increases cost, and the second inverter (300) is left out with a surplus input port to the disadvantage of efficient usage of device.