Introduction
1.3 Specifications for data transmission
ASCII protocol for RF200
8 Operating Manual, 11/2016, C79000-G8976-C329-04
Specifications for data transmission
The data transfer must meet the following specification:
With each byte, first the high nibble and then the low nibble are transferred.
e.g. in the case of 0x87: first character → 0x38; second character → 0x37.
"Words" represented in the frame structure are transferred first with the MSB. These "words"
contain, for example, the length and address information for write/read commands. The net
data is treated as bytes.
To ensure that the handling remains simple, the chaining of commands was dispensed with
in the ASCII protocol. A command is always followed by the corresponding
acknowledgement that must arrive before new commands can be sent. This means that
interface communication remains simple.
Only one command can ever be active on the reader. This rule does not apply to the
following commands:
● The "RESET" command can be sent at any time to re-initialize the reader.
● The "SLG-STATUS" command can be queried at any time.
Since the sender of an ASCII frame has no information as to whether the frame has arrived
at the other node, the new command "SLG-STATUS" (mode 0) was defined with which the
reader can be queried to establish whether a command is active or not or whether a
transponder is located in the antenna field or not.
Over and above this, the command can also be used to implement line monitoring.
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