EUCHNER EKS FSA with Profibus-DP Interface - Manual (Page 29)

Manual EKS Electronic-Key Adapter Profibus-DP
8.6 Read/write operation in conjunction with Electronic-Key read/write
8.6.1 Reading the content of the Electronic-Key
In read/write operation, following successful configuration, a transfer message with up to 128 bytes, depending
on the parameters set, is continually transferred to the input area of the bus master during each bus cycle, i.e.
the Electronic-Key adapter is read.
Information!
If a specific start address is not defined, the user data are cyclically transferred to the input area of the
bus master from byte no. 0 on the key. The number of bytes transferred cyclically depends on the
module selection in the GSD file (see section 8.1 Communication parameters (GSD file)).
Input area of the bus master
Byte no. Description Function
0 Status byte (see below)
1 Execution counter
0 ... 255, the execution counter is increased by 1 for each newly read
Electronic-Key. At a counter reading of 255 the counter is reset to 0.
Using the execution counter, the user can ensure that no Electronic-
Key is accidentally evaluated more than once.
2 Start address
First byte read in the memory area of the Electronic-Key.
After configuration, the default start address for the user data is byte
no. 0.
Number of bytes read from start address.
Max. number of bytes of user data (4/12/28/44/60/116/124 bytes)
dependent on the module selected from the GSD file.
3 Number of bytes
4 User data from Electronic-Key. Max. number of bytes
(4/12/28/44/60/116/124 bytes) dependent on the module selected
from the GSD file.
: Receive data
127
The following status information is transferred in the status byte (byte no. 0, see above):
Status byte
Bit no. Description (active with bit = 1) Function
0 Electronic-Key adapter ready
After successful configuration the Electronic-Key adapter signals that
it is ready via bit no. 0. Readiness should be continuously monitored
by the application.
1 Electronic-Key detected
The detection of a valid Electronic-Key is signaled using bit no. 1.
Using this bit, the application can detect that new data is available.
2
Reserve
3
4
Operating mode For read/write operation always set to 0.
5 Job status
Bit no. 5 is set on a status change in the EKS diagnostics byte (value
not 00
hex
, see section 8.5). This bit can be monitored by the
application.
6 Job finished Bit no. 6 indicates that a read or write has been successfully finished.
7 Job in progress Bit no. 7 indicates that a read or write is currently in progress.
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