Siemens SIMATIC Ident - Using the Acknowledgment and Command Counter

Appendix
A.2 Cyclic data
Ident profile and Ident blocks, standard function for Ident systems
Function Manual, 10/2018, C79000-G8976-C387-04
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Command / bit
Significance for RFID systems
Significance for optical readers
TP Transponder Presence
1 = There is a transponder in the
antenna field of the reader.
Manufacturer-specific
TPC Transponder Presence Changed
(only when Presence_Mode is ac-
tive)
1 = A new transponder enters the
antenna field of the reader or a tran-
sponder has left the antenna field.
The parameter is set to "FALSE"
after the successful execution of the
next "INVENTORY" (0x80, 0x81,
0x87) or "INIT" command.
Not used
Job counter (CC_L)
Less significant bit of the command counter
Job counter (CC_H)
More significant bit of the command counter
Acknowledgment coun-
ter (AC_L)
Less significant bit of the acknowledgment counter
Acknowledgment coun-
ter (AC_H)
More significant bit of the acknowledgment counter
INITACT 1= Indicates that the reader/optical reader is currently executing a start
procedure. After the bit is reset to "0", it is expected that a "Write-Config"
command sent by the block is received.
Commands other than "Write-Config" are rejected with an error. The bit is
intended to be used in the resynchronization of the acknowledgment and
command counter.
Reserved
Reserved bits
A.2.3
Using the acknowledgment and command counter
The cyclic control word is used for synchronization of frame exchange between DP
master/IO controller (the controller executing the block) and slave / I/O device (Ident device).
The transfer of non-cyclic command and acknowledgment frames via an MS1 or Record
Data CR connection can only be started when the start is indicated by the cyclic status word
of the Ident device in the acknowledgment counter.
The acknowledgment and command counter bits are used for synchronizing command
execution. The change to the command counter (executed by the Ident device) shows the
block that it can issue the next command. The change to the acknowledgment counter
shows that a command (within the Ident device) has been ended and the block can read out
the acknowledgment from the Ident device. The sequence of the change to the counters
(executed by the Ident device and monitored by the block) is the same for both counters
(acknowledgment and command counter) and is represented in the figure below.