Low-Level Protocol of ASTM communication protocol is one-way. Response is
generated after the information is sent. Response is not generated simultaneously
with communication. Unlike the other communication protocols, it does not
have master-slave relation. Both cobas e 411 analyzer and HOST enable to
initialize the communication. When establishing send system and receive system,
or when having the action of both the sender and the receiver arranged properly,
the information is communicated by the following three phases:
• Establishment Phase
• Transfer Phase
• Termination Phase
Establishment Phase
In data link layer, both sender and receiver go into one of the following statuses:
• Idle state: status waiting for becoming receiver.
• Starting Establishment Phase at the transmitting side (sender) by
sending [ENQ].
• After receiving [ENQ] from the sender the receiver sends back [ACK].
Number of sender or receiver is one at a time. Without ongoing communication
the cobas e 411 analyzer and the HOST are waiting in idle state. When a message
is sent from one side and the presentation layer requires the data link layer to
send record, one side changes its status from idle to sender. To determine the
direction of communication the sender starts the Establishment Phase by sending
ASCII Code 05h [ENQ] and turns into status sender. The receiver answers this
request by sending ASCII Code 06h [ACK] and turns into status receiver.
Transfer Phase starts when Establishment Phase is completed by receiving
[ACK]. Reception other than [ENQ] is ignored in idle status.
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