Modbus anyone ???

Anyone ever heard of Modbus ? Basically, Modbus is a communication protocol developed by Modicon systems. It is a way of sending information between electronic devices. The device requesting the information is called the Modbus Master and the devices supplying information are Modbus Slaves. In a standard Modbus network, there is one Master and up to 247 Slaves, each with a unique Slave Address from 1 to 247. The Master can also write information to the Slaves. It is typically used to transmit signals from instrumentation and control devices back to a main controller or data gathering system. Modbus is transmitted over serial lines between devices. The simplest setup would be a single serial cable connecting the serial ports on two devices, a Master and a Slave.

Ok now, the thing is, my boss asked me to analyze this VB program that he gave me. It is used to send data from the master (pc) to the slave and also to receive data from slave to the master. I was like err wtf ?? I never learn anything about it even in MMU. Frankly speaking, I know nothing on communication thingy using VB. He said after I managed to understand it, he will ask me to do stuff that are related to this Modbus thingy. OMFG !! I guess I'll try to understand Modbus first before I say to my boss, "Sir, don't give me things that are so freaky and weird like this. Please give me some other stuff to do please."

To know more about Modbus, you can click here and here.