Protocols for position value output
Leuze electronic GmbH + Co. KG
BPS 8
81
9.4.4 Binary protocol 4 request sequences
Cyclical request of position data
The simplest request sequence is the cyclical request with the function identifier 90
d
(5A
h
) Request posi
-
tion data. An answer is sent within 4 ms.
With positioning mode enabled, the response contains the defined status information and the position
data. If no valid position data can be determined, the status bit OUT is set to 1.
If positioning mode is deactivated, the BUSY response is sent; i.e. the bits DIA0 to DIA3 and the bit OUT
are set to 1 in the status byte of the response telegram. 0 is sent as a position value.
Requesting a one-time transmission of position data
In order to obtain as short a response time as possible, the following sequence must be performed with
positioning mode deactivated:
• Request telegram is sent with the function identifier 92
d
(5C
h
) Activate positioning mode.
• The BPS activates positioning mode and sends the defined BUSY response within 4 ms.
• After ≥ 35ms, a request telegram is sent with the function identifier 91
d
(5B
h
) Request one-time
transmission of position data.
• Position data are present in the BPS, and the response telegram is sent within 4 ms. Positioning
mode is automatically deactivated.
This sequence is especially suited to position data determination over long distances; i.e. where position
data are required at greater time intervals (100 ... 1,000 ms) and with reduced precision.
Advantages:
• Due to the combination of the requests Activate positioning mode and Request one-time transmis
-
sion of position data, a response is sent within 4 ms. With request cycle times of ≥ 35ms, an alter
-
nating request from Activate positioning mode and Request one-time transmission of position data
can be implemented.
• The BPS does not work permanently in positioning mode for requests with the function identifier
Request one-time transmission of position data.
Disadvantages:
• The polling sequence must be actively controlled in the control.
Behavior in the event of errors
If no current position data can be determined, the last valid position value will continue to be transmitted,
and the status bit OUT is set to 1.
In the event of protocol errors (e.g. incorrect target address, length, checksum), the request telegram is
discarded and no response is sent.
In the event of incorrect data (e.g. incorrect function identifier) and a correct telegram structure, the tele
-
gram is answered. In the response telegram, the unsupported function is entered and the position value 0
is sent.
The BPS 8 currently switches the laser off after a request pause of 10s; i.e. if no valid request is sent to
the BPS 8 during this time, the position measurement is stopped. If the BPS 8 receives a valid request
once more, the laser is switched on and position measurement is activated. Approx. 30 ms lapse until the
request is answered.
9.5
Binary protocol 6 – BPS 8 SM 10x-10
NOTE
With the BPS Configuration Tool, the user can individually adapt the binary protocols 1 and 6
to the specific requirements of the application. The binary protocols 2, 3 and 4, on the other
hand, have a fixed structure and cannot be modified.