Ack; Nack; Stop - Omron V700 series Operation Manual

(6) ACK

ACK is transmitted after receiving the response during FIFO Continue
operation, and it allows reading of the following:
n Command
Command Terminator
"1" "1" CR
n Response
There is no response.

(7) NACK

When the High-end device was not able to receive a response correctly,
NACK is transmitted to demand the response to be transmitted again. When
the Reader Writer receives this command, the most recent response will be
transmitted again.
n Command
Command Terminator
"1" "2" CR
n Response
The most recent response will be transmitted again.

(8) STOP

The STOP command is used to stop the Reader Writer executing a command.
When the Reader Writer receives this command, it immediately stops the
execution of the current command and sets on stand by mode for a new
command.
n Command
Command Terminator
"1" "3" CR
n Response
Completion Terminator
Code
"0" "0" CR
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