With the example of the MELSEC-FX2N PLC and the FR-S500 inverters,the port communication technology of VVVF are introduced,and by the part of the communication control program,the paper explains the method of the port communication program by PLC.
The whole network is operated under the management of an experimental loop network communication control program (ELNCP) with the function of shared hardware resource and partially shared software resource.
The host communication program and the interface card communication control program make up of the DNC interface software. The interface card communication control program which was written in TMS320F2812 DSP language can receive the signal instruction from DNC host and communicate with CNC system or DNC host according to the instruction types.
VB has not afforded the function to operate the I/O directly, which makes it difficult to program the system interface. This paper introduces the design of software for serial communication using Visual Basic and provides MODEM communication control program in VB on Windows, which makes the PC controlled MODEM communicate with long-distance one specially controlled by the PC. And the paper presentes an implementation method of the software to enhance the reliability of the data transmission.
The prepared programs included a database manager (on the mainframe computer), a user interface program (on the PC), and a communication control program that connected the mainframe computer with the PC.
With the dual purpose of teaching and research on computer network, a small dis tributed control experimental loop computer network system (experimental loop network for short) has been developed. The whole network is operated under the management of an experimental loop network communication control program (ELNCP) with the function of shared hardware resource and partially shared software resource.
This paper provides MODEM communication control program in VB on Windows, which makesthe PC controlled MODEM communicate with long-distancc one specially controlled by the single chipmicrocomputer. The communication program and itsflow chart are given in the paper.