Roche/Hitachi cobas c 311 analyzer ASTM communication protocol
Definition of Communication Protocol
Roche Diagnostics May 2011
Host Interface Manual – Version 1.3 D-6
Transfer phase
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. According to the above,
there are three options for HOST to respond the
communication of the frame.
- HOST sends [ACK] or [EOT].
cobas c 311 analyzer sends the next record. cobas c 311
analyzer has data that is to be communicated. cobas c 311
analyzer continues to send records. (It is started with
Establish phase.)
- HOST sends characters other than [ACK] or [EOT].
cobas c 311 analyzer repeatedly sends record. This cycle is
repeated until “number of retry in case of error” reaches six.
At this moment, cobas c 311 analyzer starts Termination
phase and displays an error message by sending [EOT].
- No response from HOST
cobas c 311 analyzer starts Termination phase by sending
[EOT] after 15 seconds and displays an error message.
Response depends on how HOST responds to frame
communication from cobas c 311 analyzer. When cobas c
311 analyzer is in the receiving status and is waiting
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, cobas c 311 analyzer responds by [ACK]. When the
frame is incorrect, the incorrect frame is rejected and [NAK] is
returned.
- HOST does not complete frame communication.
Time-out occurs when receiving unfinished frame and at the
same time [EOT] is not received after 15 seconds counted
from the last communication of [ACK] or [NAK] from cobas c
311 analyzer. cobas c 311 analyzer is turned into idle status
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