Specifications

1070 072 131-102 (96.08) GB
BUEP03E Protocol 8-13
If a fault occurs (e.g. invalid parameters, system bus fault...), the com-
mand chain is terminated immediately and the fault message is returned
with the interlinking depth.
In order to establish a single communication with a peripheral, the inter-
linking of the following commands must be indicated with the Start com-
mand.
- Set Receive mode
- Request data
- Enable Receive
- Acknowledge Receive
The Data Copy command is not inserted into the command chain, but is
activated parallel to Receive. The Start command starts the command
chain.
Start (1)
Receive Mode (2)
Request Data (3)
Receive (4)
Peripheral Data (5)
Data Copy (6)
Acknowledge rec. (7)
Fig. 8-7 BÜP03E — Chronological sequence of a single communication
(1) Start the command chain
(2) Set receive mode (end character, Receive-data length).
Do NOT specify a start character, otherwise a peripheral NAK is not reco-
gnised as BÜP03E would be waiting for the start character.
(3) Request data by "Transmitting" a control text.
(4) Switch ON the (unrestricted) receive.
(5) Peripheral responds to the data request by BÜP03E.
(6) At the same time as the receive process, copy the data into the
PLC Receive buffer and analyse. There are two options available for this
step:
- Peripheral transmits the data after the data request has been suc-
cessfully received by BÜP03E . The data is retrieved until, e.g. an end
identifier, is recognised.
- Peripheral transmits, e.g. an NAK, and requests a repeat of the
data request. In this case either the communication can be terminated
with a Terminate Job sequence or the step (3) can be repeated.
(7) Communication is terminated via the stipulated conditions. The re-
ceived data is checked by the PLC program and positively acknowledged
if correct. If a fault occurs, the received data is negatively acknowled-
ged and communica tion can be restarted at Step (1).