Protocols

GTXC SERIAL COMMUNICATION PROTOCOL

The displays can be linked to a computer through a serial communication RS232, RS485 and CURRENT LOOP using the following DEFAULT settings:

BAUD RATE : 1200 – available up to 19,200
START BIT : 1
STOP BITS : 2
PARITY : NONE

8 Bit ASCII code compatible with extended IBM ASCII code.
These are the default settings which can be changed using the dip-switch on the SERIAL COMMUNICATION BOARD.

  CONNECTING THE COMPUTER TO THE SIGN

When you power up - the sign will perform a self-test and display the results on the screen.  The setting of the "Serial Communication Board" will be displayed.  Be sure to use the same settings on the PC.

Using RS232
A Direct connection via RS232 can be used only for a short distance - up to approximately : 100 metres. Only 3 wires are used and these must connect as follows:

PC SIDE

SIGN SIDE
DIN.... 25 DIN.... 9 Round DIN.... 5
Signal  
TXD  PIN  2 PIN  3 PIN  5
RXD  PIN  3 PIN  2 PIN  3
GND  PIN  7 PIN  5 PIN  4

Using RS485
Connect RS232 to the RS485 converter, between the PC and the sign.
This international standard is more suitable for long distance communication, as well as Multidrop communication.  {Few signs can be connected on Two-Way communication to the Host [PC] }

     PC       RS232              RS232 / RS485   RS485 Up to 1000 mts     
                   (4 wires)               Converter       (2 wires + screen)         RS485 Interface

The PC is linked to the RS485 converter via 4 wires namely:~
                TXD     Transmit data  from PC
                RXD     Received data to PC
                DTR     Controls Traffic flow : +12V => TX Mode,  -12V => RX Mode.
                GND     Ground

Since RS485 only uses 2 wires, only one device can send data at a time.
The PC downloads a page of text, the sign checks the integrity of the message and if it is OK - it will transfer the page from the temporary RX Buffer into the message buffer.
If the acknowledge BIT on the Serial Status Byte is set (B3), then the sign will send "Acknowledge" back to the PC.
In order for the PC to get the reply {when RS485 is used} DTR needs to be at - 12V [RX Mode].  Once the reply has been sent, the PC can send the next page etc..

When the last page has been sent, be sure that BIT 2 - on the "Serial Status Byte" has been Reset ( = 0), so that the new message will be displayed immediately. When this BIT is set, it instructs the sign that more pages are 'coming' and therefore, the sign will 'wait' for these pages and will not display the new message... however if no new data is received within 40 seconds.  It will consider the last valid page - received as the last page and the sign will then display the new message.

   COMMUNICATION PROTOCOL

These signs can be programmed for one way or two way communication by setting the relevant bit as explained below (should a two way com. be selected, be sure that your hardware can support it !). The message should be sent to the sign page after page. When a page is successfully received by the sign and provide that the "ACK" bit is set, it will respond with an "ACK" (decimal VALUE 6). Should the message corrupt the sign will respond with "NAK" (decimal value 21) if the "ACK" bit is on. Once a page was successfully received by the sign the next page can be sent and so on. A delay of up to 1 sec can be expected between the transmission and the response by the sign for the first page and up to 0.5 sec for every consecutive page. The first page to be sent to the sign is page 0 which consist of the current time and date from the computer & thereafter the message.

 BYTE           DESCRIPTION              DECIMAL VALUE                  COMMENTS

1                      Header Sync                              00
2                      NOL                                            ??                                  (number of text lines on the sign)
3                      Sign Address                            xx                                   (1-127 , 0 = "ALL CALL")
4                      Etx                                              03                                      End of header.
5                      Serial status flag                      SERST                              (See note # 1)
6                      Page number                            X 100                                 (ASCII)
7                      Page number                            X 10                                   (ASCII)
8                      Page number                            X 1                                     (ASCII)
Message text or time and date (See details below)
                       EOT                                           04                                       END OF TEXT
Last byte      Checksum                                 ??

(The checksum is an exclusive 'or' function bit by bit starting at the SYNC. up to and including the "END OF TEXT" byte 04).

* NOTE 1 SERIAL STATUS

BO , B5 = 0
B1= 1 = ) "INTERRUPT mode " = 0 =) Normal DISPLAY mode
B2= 1 = ) More pages to come, = 0 = Last page
B3= 1 = ) "ACK" Requested , = 0 = No "ACK" required
B4= 1 Schedule mode operation = 0 =) No schedule operation.
B6-B7 All = 1

IMPORTANT NOTICE : if schedule mode is NOT selected then bytes 9 - 25 inclusive on all DATA pages MUST BE OMITTED ! ! !

IT IS NOT NECESSARY TO SEND PAGE NUMBER 000 EVERY TIME.

MESSAGE FORMAT

PAGE NUMBER 000

This page consists of the time, date and day of the week.

BYTE DESCRIPTION (ALL BYTES IN ASC11)

9 Hours MSB
10 Hours LSB
11 Minutes MSB
12 Minutes LSB
13 Seconds MSB
14 Seconds LSB
15 Date MSB
16 Date LSB
17 Month MSB
18 Month LSB
19 Day MSB ALWAYS = 0
20 Day LSB DAY OF THE WEEK (1=SUNDAY, 2=MON)

DATA PAGES (001 TO Last page)

BYTE DESCRIPTION (ALL VALUES IN ASC11)

9 Start date day (MSB) *
10 Start date day (LSB) *
11 Start date month (MSB) *
12 Start date month (LSB) *
13 Start date day (MSB) *
14 Stop date day (LSB) *
15 Stop date month (MSB) *
16 Stop date month (LSB) *
17 Start time hours (MSB) *
18 Start time hours (LSB) *
19 Start time minutes (MSB) *
20 Start time minutes (LSB) *
21 Stop time hours (MSB) *
22 Stop time hours (LSB) *
23 Stop time minutes (MSB) *
24 Stop time minutes (LSB) *
25 Weekly status (see note # 2) *
26 TEMPO for this page (NOTE # 3).
27 FUNCTION of this page (NOTE # 4).
28 PAGE STATUS (SEE note # 5)
29-END ASC11 TEXT FOR THE PAGE.

NOTE 2 : WEEKLY STATUS

B0 Sunday (1 = ON , 0 = OFF)
B1 Monday (1 = ON , 0 = OFF)
B2 Tuesday (1 = ON , 0 = OFF)
B3 Wednesday (1 = ON , 0 = OFF)
B4 Thursday (1 = ON , 0 = OFF)
B5 Friday (1 = ON , 0 = OFF)
B6 Saturday (1 = ON , 0 = OFF)
B7 =1 Always

* NOTE # 3 : TEMPO

This byte determines the duration that this page will FREEZE on the screen every time it is displayed.

B0 -B3 Duration this page will be displayed see table below.
B4 - B5 Display status bits
0 0 This page is in "Timer" mode and will display as set by the scheduled time.
0 1 This page is always ON
1 0 This page is always OFF
1 1 Invalid.
B6, B7 Both bits must always be set.
B0 - B3 Setting

TEMPO :        1    2    3    4    5    6    7    8    9
TIME (sec) :  2    5    10   20   30   45   60   90   120

* NOTE # 4 : FUNCTION FOR THIS PAGE

B3 /  B2 / B1/ B0 / FUNCTION

0 0 0 0 AUTO (RANDOM SELECT ANY FUNCTION)
0 0 0 1 APPEAR
0 0 1 0 WIPE
0 0 1 1 OPEN
0 1 0 0 LOCK
0 1 0 1 ROTATE
0 1 1 0 RIGHT
0 1 1 1 LEFT
1 0 0 0 ROLL UP
1 0 0 1 ROLL DOWN
1 0 1 0 PING PONG
1 1 1 1 SLIDE
1 0 1 1 FILL UP
1 1 0 0 PAINT
1 1 0 1 FADE IN
1 1 1 0 JUMP

IMPORTANT NOTE : In SLIDE mode the bottom line will scroll across the screen from right to left in a speed set by the TEMPO value (Speed 1 is the fastest and 9 is the slowest.) Therefore the length of this line is flexible.

B4 = 1 = > CLOCK on top line.
B5 = 1 = > TEMPERATURE on top line.
B6, B7 = 1 Both are always "HIGH".

* NOTE # 5 : PAGE STATUS

B0 = 1 => Top two lines joint in "BOLD" mode
B1 = 1 => Bottom two lines are joint in "BOLD" mode
B2 Reserved
B3 Reserved
B4 = 1 => AutoCentre ON (The text will be centred on the screen).
B5 = 1 => Foreign LANGUAGE, = 0 = > English
B6 = 1 => Background colour ON. (Will automatically select as the opposite of the foreground colour. IE If RED IS SELECTED-BACKGROUND IS GREEN
B7 Always "High".

CHANGE LETTER APPEARANCE ON THE DISPLAY

In order to change the appearance of letters in the display the following controls can be used.

A control block consist of 2 bytes :

1ST byte : CONTROL CODE = 28 bcd, [ICHEX]

2ND byte COMMAND byte. Following commands are available.

F : FLASH CHARACTERS
E : ENLARGE CHARACTERS
R : CHANGE COLOUR TO RED. (ONLY ON COLOUR SIGNS ! )
G : CHANGE COLOUR TO GREEN. (ONLY ON COLOUR SIGNS !)
Y : CHANGE COLOUR TO YELLOW (COLOUR SIGNS ONLY ! )
M : MULTICOLOUR i.e. : TOP RED CENTRE YELLOW BOTTOM GREEN
D : RETURN TO DEFAULT SETTING. IE NORMAL (NOT ENLARGED) RED LETTERS NOT FLASHING

Every page starts with the default settings.

EXAMPLE : THE FOLLOWING STRING :
"POLYCOMP" (28) "G IS" (28 "F" (28) "M THE" (28) "F" (28) "E" BEST" WILL DISPLAY : "POLYCOMP IS THE BEST"
RED,  GREEN,  MULTICOLOUR AND FLASH MULTICOLOUR AND ENLARGE
IN THIS EXAMPLE : TEXT BETWEEN INVERTED COMAS " " is acs11 characters         NUMBERS BETWEEN BRACKETS ARE IN bcd values.