Connect Tech Blue Heat/Net Sync User Manual
Flowchart of Special Operations Mode using the reset button
Power Up
Reset Yes
Button
Held
No
Continue
Booting
Increment
Selection
Show
Selection State
On Port LEDs
Pressed
ResetHeld Button
Wait for
Button
Release
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.
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