Intermec nx Reference Guide
RS-232 input devices
MB/NX/RM/00/E/970131
115
ENQ / ACK / NAK software protocol
The RS-232 input device connected to the MicroBar NX can synchronize communication by
sending an ENQ character (05h). The MicroBar NX answers with an ACK character (06h)—
even if ENQ/ACK/NAK has not been activated in the MicroBar NX.
sending an ENQ character (05h). The MicroBar NX answers with an ACK character (06h)—
even if ENQ/ACK/NAK has not been activated in the MicroBar NX.
When a message—terminated with the selected end-of-message character—is received
from the RS-232 input device, the MicroBar NX sends an ACK character if the message is
understood, or a NAK character (15h) if the message is not understood. The ACK character
is sent when transmission has been completed.
from the RS-232 input device, the MicroBar NX sends an ACK character if the message is
understood, or a NAK character (15h) if the message is not understood. The ACK character
is sent when transmission has been completed.
The hardware/software protocols timeout for RS-232 input devices is unlimited and can not
be configured.
be configured.
Typical ENQ / ACK / NAK scenarios
RS-232 input device
RS-232 input device
message
(not OK)
NAK
ENQ
ACK
(clears message)
repeats message
(OK)
ACK
ENQ
MicroBar NX
MicroBar NX
message
(OK)
ACK
(clears message)
ACK