TIWAY I Network Communication
3-10
S5 UniLink Adapter Installation and Operation
3.6 Transmitting with the 3964R Procedure
NOTE: The term procedure refers to the device initiating the transfer, and
the term partner refers to the receiving device.
To establish the link, the procedure sends the control character STX. If the
partner replies within the time allowed of 2000 ms, the procedure starts the
transmission. If the partner answers with NAK, any other character (except
DLE), or if there is a timeout, then the attempt to establish a link has
failed. After a total of six unsuccessful attempts, the procedure gives up,
signals there is an error establishing the link, and sends the character NAK
to the partner.
If the link is successfully established, the information data to be sent to the
partner is immediately sent to the partner at the selected data rate. The
partner monitors the time between the characters as it receives them. The
time between two characters must not exceed the character delay time of
220 ms.
While the information data is being transmitted, the partner sends the
character NAK, the procedure breaks off and repeats it as previously
described. If any other character is received, the procedure waits for the
character delay time (220 ms) to elapse and then sends NAK to reset the
partner. Then the procedure begins the transmission again with the link
establishment STX.
Each DLE character sent is found in the transmission as two DLE
characters (DLE doubling), i.e., the data (10H) is sent twice.
After sending the information data the procedure adds the characters DLE,
ETX, and BCC as end identifier and waits for an acknowledgment.
If the partner sends the character DLE within the time allowed (2000 ms),
the information data was received without errors. If the partner replies with
any other character (except DLE) or there is a timeout, the procedure begins
the link establishment again with STX. After a total of six unsuccessful
attempts to send the information data, the procedure breaks off the
attempt, signals an error, and sends NAK to the partner.
Link Establishment
Transmission
Acknowledgment
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