Break Free from the "Computer – Device Driver – Serial Device" Headache
All serial devices have one thing in common. A dedicated device driver for the
serial device must be installed on the computer to which the device
is connected. If the driver is not installed or configured properly,
the computer and serial device will not be able to communicate
with each other. As the data stream passes between a serial port
and network port, or between two serial ports through the embedded
computer, the data is processed by one or more of the installed
device drivers.
Inserting the classical "computer – device driver – serial device" setup into the modern plant-wide control system can create a big headache for
programmers. The three biggest problems are:
1. A "timer" subroutine that runs on the embedded computer must be created to
query/control each type of serial device periodically. This may
sound easy enough, but in fact it can be surprisingly difficult
to create
suitable timer routines to control devices.
2. Data from each serial device must be converted to a format compatible with TCP/IP transmissions, and if two serial devices need to communicate directly with each other, additional code must be created to make this serial-to-serial communication possible.
3. In general, you must write new code for each data stream channel to ensure that data is transmitted successfully through the channel.
