Protocol: COIN VALIDATOR L86S PS 4
10044 UK 11 -2003
NEGATIVE ACKNOWLEDGEMENT (NACK)
This is used when there has been an error in the reception. It has the following format:
[00H]
[FFH]
[Checksum=01H]
DIALOGUE FORMAT
The communication is half-duplex: A command is not replied to until it has been received
completely.
Each communication sequence consists of two messages with the previously mentioned
structure: the command and the reply to the command once it has been processed.
The communication is multi-master: either of the two, Validator or Telephone can start a
communication sequence, with the followings limitations:
ÔThe Validator only begins communication to communicate there is a measured and
validated coin.
ÔIf the Validator is measuring a coin and a valid message arrives (a complete block
with the checksum correct), it stops measuring the coin and starts processing the
command.
TEMPORARY REQUIREMENTS
Maximum Time between bytes
The maximum time between two bytes in the same message is 800 milliseconds. If
this time is exceeded the communication programme resets all its variables and
prepares a new message.
The time between bytes from Validator to Telephone is 200 milliseconds, except
between the first and the second, which is 400 milliseconds.
Between command and reply
The maximum time to reply to a command depends on the time it takes to process
the command.
The default time is 30 milliseconds for commands, if the contrary is not specified in
the command definition.
Maximum time without commands
The maximum time the Validator is “awake” and without receiving commands is
500 milliseconds. After this time the Validator switches off.
When a coin enters the Validator this time is not taken into account (The Validator
switches off when the coin leaves).
