Using Dpi/Ip Procedure; Function And Characteristics; Protocol Parameters - Balluff BTL6-P111-M-A1-S115 series Datenblatt Und Anleitung

BTL6-P111-M_ _ _ _-A1-S115
Micropulse AT Transducer in round profile housing
7

Using DPI/IP Procedure

7.1 Function and
characteristics
DPI/IP procedure uses two operat-
ing modes: DPI measurement mode
and IP data protocol mode.
DPI = digital pulse interface
IP = integrated protocol
DPI measurement mode:
The INIT pulse is sent to the BTL at
regular intervals over the INIT line;
the rising edge of this pulse triggers
a measurement
(INIT pulse where T < 5 µs = Start/
IP
Stop measurement ➥ ➥ ➥ ➥ ➥ Fig. 2-1).
IP data protocol mode:
If the length of the INIT pulse T
increased to approx. 15 µs, the
transducer switches from DPI mea-
surement mode (➥ ➥ ➥ ➥ ➥ Fig. 7-1).
Following the INIT pulse, a charac-
ter string (Command) is sent to the
BTL as a command. The BTL does
still send the Start pulse over the
START/STOP line as a response,
but instead of the Stop pulses a
character string (Response) contain-
ing a response appropriate to the
command is sent to the controller.
Each character in the transmission
protocol has the following bit struc-
ture:
...
Start Bit0 Bit1 Bit2 Bit6 Bit7 PBit Stop
T
Bit
Start-Bit Start-of-Frame-Bit
Bit0...Bit7 8 data bits
PBit Parity-Bit (Even-Parity)
Stop Stop-of-Frame-Bit
T 4 µs (bit length at a
Bit
data rate of 250 Kbps)
Data integrity when transmitting the
character string is achieved using
parity and CRC16 checking with the
polynomial X16+X12+X5+1 (corre-
sponds to 0x1021). In case of a
transmission or protocol error, the
BTL sends out a corresponding
error message in reply.
6 6
english
INIT
START/STOP
Fig. 7-1: Principle of data transmission with IP data protocol
T INIT pulse < 5 µs
IP
or:
T approx. 15 µs
IP
Command Command for requesting BTL data
((information stored in the BTL)
T 3 µs to 5 µs
Start
is
IP
T > 50 µs
D1
Response Response based on the request
or: Error message
7.2

Protocol parameters

Table 7-1: List of request/response parameters
CI Command ID
CR Command Response
LEN Length of data D0 ... Dn
D0 ... Dn Data frame
CRC16 from CI / CR to Dn, ➥ ➥ ➥ ➥ ➥ section 7.3
CRC
Command
T T
D1
IP
T
Start
Start/Stop measuring technique (➥ ➥ ➥ ➥ ➥ Fig. 2-1)
operation with IP data protocol (➥ ➥ ➥ ➥ ➥ Fig. 7-1)
CI LEN CRC CRC
CR LEN D0
...
Response
...
...
Dn CRC CRC