15.8.14
UNIGATE
®
fieldbus gateway UNIGATE
®
CL PROFINET 2Port V. 1.6
22
Deutschmann Automation GmbH & Co. KG
Implemented protocols in UNIGATE® CL with Universal Script
Receive data at the RS interface is evaluated in accordance with the configured protocol, and the
data field (data area (see chapter 10.2.1)) is sent to the fieldbus Master. If more characters have
been received than the fieldbus block length, the trailing bytes are truncated and an Rx Overrun
is indicated. If less have been received, padding with 0 occurs. If the "Length byte" is active, the
number of received useful data items is entered there. If the, "Trigger byte" is active, this is incre-
mented by one after each complete reception operation at the RS interface.
10.3 Protocol: 3964(R)
The 3964 protocol is used to transfer data between two serial devices. One partner must be a
high-priority partner and the other must be a low-priority partner in order to resolve initialisation
conflicts.
10.3.1
Data structure 3964R
10.3.2
Protocol definitions
STX
Data
DLE
ETX
BCC
The telegram format is as follows:
•
The received net data is forwarded (transparently) in both directions unchanged.
Attention:
The DLE-doubling is excluded from it; that means one DLE (10H) on the bus-side is
sent on the RS-side twice. A double DLE on the RS-side is only sent once to the bus-master.
•
Data blocking is not scheduled.
•
The net data length is restricted to 236 bytes per telegram.
•
Communication always runs between high-priority and low-priority communication partners.
10.3.3
Data communication
10.3.3.1 Initiation of data communication by the low-priority user
If the low-priority user also receives an STX in response to a transmitted STX, it interrupts its
transmit request, reverts to Receive mode and acknowledges the received STX with DLE.
A DLE in the data string is duplicated and included in the checksum. The BCC is computed from
XORing all characters.
10.3.3.2 Conflicts
10.3.3.3 Timeout times
The timeout times are preset by the definition of the 3964R protocol and cannot be overwritten !!!
tq = acknowledgement timeout time (2 s).
The acknowledgement timeout time is started after transmission of control character STX. If no
positive acknowledgement arrives within the acknowledgement timeout time, the job is repeated
(max. 2 x). If it has not been possible to complete the job positively after two repetitions, the
high-priority device nevertheless attempts to establish contact with the low-priority partner by
transmitting STX (cycle corresponds to tq).
