STANDARD SERIAL COMMUNICATION INTERFACE and ...

Standard Serial Interface Protocol Description
default font, each character will occupy a 8x10 pixel space. Up to 40 characters/text line and
up to 8 text lines/display can be output using this default font.
f) (DC3) = Turn ON Underline control character. All characters entered in field 6 after the
reception of this control character will be output in Underline format. The absence of
this control character will command the respective sign to output the display with the
default non-underlined mode.
5.6.2 Maximum Number of 320x80 Messages
As indicated in the “” references in table 5.6.1, the 320x80 controller module can store several
messages or pages of data for the respective number of display assign to the controller module. To
maximize the amount of messages to be stored in the controller module, the controller uses a dynamic
memory allocation method. Each message type assign for each display with a given message (or
“Page”) is allocated a fixed memory space, based on the message type for the given display. The
dynamic memory allocation firmware uses a “link list” to place each display image in consecutive section
of the controller RAM memory.
The following memory space allocations are assigned to the available message types:
# Message Type Field #4 Command
Designation(s)
Fixed Memory
Space Allocation
1. Full Screen Text “0” 553 Bytes / Display image
2. Full Screen Graphic “1” 3214 Bytes / Display image
3. Partial Screen Text, Dynamic “2”, “4” and “6” 68 Bytes / Display image
Update Text, Flashing Text
4. Partial Screen Graphic “3” 2174 Bytes / Display image
5 Dyanamic Update Partial Screen
Graphic
“5” 654 Bytes / Display image
Table 5.6.2: Controller Memory Space Allocations for Different Types of Message Data
As indicated previously, the 320x80 controller module will load display message data into memory
sequentially, into the next available memory location. Since the controller has a finite amount of memory
storage capacity, the interface software (“320x80Soft”, or equivalent) will need to either keep track of the
amount of bytes used in the respective controller address prior to transmitting, or the controller will need
to be “asked” the amount of available memory for an additional display message storage. For instance,
the maximum amount of message data that can be loaded into a 320x80 controller can not exceed
43,817 bytes.
The following items pertain to maximizing the number of complete messages (or “pages”) stored by a
320x80 controller module:
o To maximize the number complete messages to be loaded into a controller module, use textbased
messages (full, partial, flashing or partial screen text dynamic update) whenever possible.
For instance, a 320x80 controller can store only 9 complete full screen graphic messages {3214
[bytes/message] x 13 [messages] = 41,718 [bytes]}, whereas the same controller can store 79
complete full screen text based message {553 [bytes/message] x 79 [messages] = 43,687
[bytes]}, which is less than the 43,817 bytes capacity. Additional message storage capacity can
be obtained if partial screen text images are used whenever possible.
Standard Serial Communication Interface Description, © 1998-2002 Kent Displays Inc., doc. # 25016 Revision T, Page 37 of 52