of 61 Host Interface Manual for use in the US
After receiving frame, sender discontinues communication until receiving the
response or occurrence of time-out. Usually the receiver notifies by sending
[ACK] that it successfully received the last frame and completes its preparations
to receive the next frame. The receiver notifies by sending [NAK] that the last
frame was not received and it is waiting for receiving the frame.
HOST in status receiver According to the above, there are three options for HOST to respond
the communication of the frame.
HOST sends [ACK] The cobas e 411 analyzer sends the next frame. If the cobas e 411
analyzer has data to be communicated, the cobas e 411 analyzer
continues to send frames.
HOST sends characters other The cobas e 411 analyzer repeatedly sends the frame. This cycle is
than [ACK] repeated until the number of retry in case of error reaches six. At this
moment, the cobas e 411 analyzer starts Termination Phase and
displays an error message by sending [EOT].
No response from HOST. The cobas e 411 analyzer starts Termination Phase by sending [EOT]
(timeout) after 15 seconds and displays an error message.
Response depends on how HOST responds to frame communication
from the cobas e 411 analyzer.
HOST in status sender When the cobas e 411 analyzer is in the receiving status and is waiting
for communication from HOST, there are the following three
scenarios.
HOST sends frame characters After the complete frame is received, the frame No. and the checksum
are checked if they are correct. When the frame is correct, the cobas e
411 analyzer responds by [ACK]. When the frame is incorrect, the
incorrect frame is rejected and [NAK] is returned.
HOST does not complete Time-out occurs when receiving unfinished frame and at the same
frame communication time [EOT] is not received after 15 seconds counted from the last
communication of [ACK] or [NAK] from the cobas e 411 analyzer.
The cobas e 411 analyzer changes to idle status by deleting the last
incomplete message. The line is deemed to be neutral status.
HOST sends [EOT] The cobas e 411 analyzer changes to idle status. Only completely
received frame is deemed to be effective.
Chapter Transfer Phase shows the flowchart of three types of response against
frame communication. An entry point C is selected when Establishment Phase is
completed without any trouble. The entry point C is also the reentry point when
the following frame communication is succeeded. An entry point D is for
retrying when [ACK] is not responded. An entry point E shows change of the
last Phase of this layer.
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