47
UK
12.8 Module “RWH_RW”, Read User data of the RFID tag asynchronously
In this mode the User data of the RFID tag can be read automatically without sending any read request .
This mode is suitable if the user know when the RFID tag is present in front of the read/write head .
Additionally this mode allow the fastest detection of RFID tag cause no command request need to be
send to the evaluation unit . Please note that the User data is transmitted in real time and the PLC cycle
time need to be about factor 2 shorter as the RFID tag is detected by the read/write head .
PLC process data output image (Module RWH_RW)
Byte no .
Bit
7
6
5
4
3
2
1
0
1
0
DR (3)
ER=1 (2)
UR=1 (1) RD=1 (2)
0
AO=0
0
2
Read data length
3
16 bit start address [D15…D8]
4
16 bit start address [D7…D0]
5
Not used
,,
20
Not used
Description Byte 1, “Control byte”:
Bit
Value
Description
Remark
AO
0
“Antenna field on” request inactive
Activate the antenna field
RD (2)
UR (1)
ER (2)
1
Mode “Receive User data automatically”
selected
(1) Must be set to 1 to access the User data of the RFID
tag
DR (3)
0
No read request
Data byte 2 … 20 of the process data input image is set
to 0x00 .
0->1
Read diagnostics of the evaluation unit
-
1
Diagnostics read request active
DR must be kept on 1 until the command response is
available .
(1) Mode can be changed every time if bit “RD”, “ER” and “DR” is set to 0 => no command active .
(2) If bit ER and bit RD is set to 1 a reading process of the User data of the RFID tag is started when a
change of the bit TP is detected . So the user gets only a message from the evaluation unit if the state of
the RFID tag changes from “not present to present” and from “present to not present” . This help to limit
the requests which are needed to be send from the PLC .
(3) Reading of the diagnostics is only possible if ER und RD is set to 0 . Diagnostics is only available, if bit
“Diag” within the response data is set . Otherwise the response data will return default data “0x00” within
byte 2 . . .20 of the response data .
Description Byte 2, ”Read data length”:
Read data length, limited to a maximum number of 16 bytes .
Description Byte 3... 4, ”16 bit start address”:
Start address of the RFID tag User data where the data has to be read from .
Description Byte 5... 20, ”Not used ”:
These bytes are ignored .
