EUCHNER
Hand-Held Pendant Station
HBAS-094594
095640-02-02/06
Subject to technical modifications
Page 7 / 40
3. Data transfer
3.1 Protocol 3964 R
The protocol for the serial interface corresponds to the procedure 3964 (R).
The data transfer is initiated by sending an
STX
character. The receiver must answer with
a
DLE
character within the stipulated acknowledgement delay of 500 ms.
The transmitter then switches to send mode.
If the receiver answers with
NAK
, a character <>
DLE
, with an incomplete character, or the
acknowledgement delay elapses, then the attempt to establish the connection has failed.
After three unsuccessful attempts, the transmitter interrupts the procedure and outputs an
error message to the higher level program.
If the connection is successfully established (receiver answers with
DLE
within the
acknowledgment delay), then the characters in the send buffer are sent to the receiver.
The receiver expects the data within a character delay of 128 ms. If this delay is not met,
the receiver sends an NAK character.
The transmitter then tries again to send the message.
After three unsuccessful attempts, the transmitter interrupts the procedure and outputs an
error message to the higher level program.
After the content of the buffer has been sent, the transmitter adds
DLE
and
ETX
as an end
marker. Then the
BCC
(Block Check Character) is sent. The receiver must confirm correct
reception with
DLE
within the acknowledgement delay, or indicate erroneous transfer
with
NAK
.
