EUCHNER HBAS - Manual (Page 10)

EUCHNER Hand-Held Pendant Station
Example of a possible collision:
HBAS sends a key change STX ??
The control system sends "LCD text" STX ??
Solution:
First the HBAS sends then the control system sends
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HBAS STX 31H DLE ETX BCC DLE DLE
Control
system
STX DLE DLE STX 6CH 25H DLE ETX BCC
Structure chart send/receive routine for the control
Check input buffer for new character
If receive new character
then else
call Receive routine
Wait for new character
If new character = DLE
then else
If new character = STX
then else
If new character = DLE
then else
Send NAK
Send NAK
call Status check
call Status check
Send data
Wait for new character
Send data
Start new
transfer routine
Send STX
Receive routine Status check
Send status request (#)
Wait for status information
Evaluate status
Send DLE
Check input buffer for new character
If receive new character
then
else
If new character = STX
then
Receive data block
Check BCC
If BCC = ok
else then
Send DLE
Send NAK Evaluate key change +
error byte
Send NAK
exit sub
else