Connect Tech BLUE HEAT/NET SYNC CTIM-00044 - Manual (Page 71)

Connect Tech Blue Heat/Net Sync User Manual
Revision 0.01 71 71
Flowchart of Special Operations Mode using the reset button
Figure 31: Bootup Sequence via Reset Button
Asynchronous Communications Tutorial
The Blue Heat/Net Sync features four synchronous/asynchronous serial communication ports.
Asynchronous communication is a simple, cost effective means of terminal serial
communication. For this reason, it is widely used for communications on personal computers,
bar codes readers, printers, terminals and much more. The following documention represents a
basic tutorial for asynchronous communications. For a tutorial on synchronous communications,
please refer to the Z16C32 IUSC User’s Manual (DOC ID DC8292) on the
Zilog website.
In asynchronous serial communication, the electrical interface is held in the idle position
between characters, also referred to as “mark”. A change in signal level (known as space level)
indicates the start of transmission of a character. The receiver recognizes this change as a “start
bit”. Once the start bit has been sent, the transmitter sends the actual data bits. In typical
asynchronous communications there may be 5, 6, 7, or 8 data bits, depending on the application.
Both the receiver and the transmitter must be set to the same number of data bits, baud rate and
stop bits. Stop bits can be 1, 1.5, or 2 bit periods in length. When the transmitter has sent all the
data bits, it sends a stop bit. This stop bit signals to the receiver that the data has finished
transmission. The stop bit is the same state as the idle or mark state.
Reset
Button
Held
Power Up
Continue
Booting
Show
Selection State
On Port LEDs
Reset
Button
Increment
Selection
Pressed
Held
Wait for
Button
Release
Yes
No