Siemens SIMATIC Ident RF200 - Communication in Scan Mode

Scan mode function extension for ASCII readers
3.3 Communication in scan mode
ASCII protocol for RF200
26 Operating Manual, 11/2016, C79000-G8976-C329-04
3.3
Communication in scan mode
The communication between host and reader in scan mode occurs using the interface
parameters set in the reader. The interface parameters are set as follows in the factory:
● Physical structure: RS232
1)
● 8 data bits, 1 stop bit
1)
● No parity
● Transmission speed: 38.4 kBd
1)
This value cannot be changed in RF200 readers.
Frames use binary communications.
Frame structure:
A frame from the host to the reader is structured as follows:
Table 3- 3 Example of a frame structure
Command parameter
Frame parameter
Command
Status
Count
Byte 1
...
Byte x
BCC
The acknowledgement from the reader to the host is structured as follows:
Table 3- 4 Example of an acknowledgment
Command
Error code
BCC
The reader transmits the acknowledgement after it has finished performing the command.
Conditions for frame transmission
The following conditions apply for frame transmission:
● The BCC checksum is calculated by simple XORing of all bytes.
● If an interface parameter is changed (baud rate, parity): the acknowledgement is sent with
the old setting. The new setting then takes effect (scan data, next frame).
After connecting to the host, the reader automatically uses the configured parameters to
transmit data to the user program via the serial interface. This requires the presence of a
transponder in the antenna field. Data transmission can only be secured by assigning a
parity bit. Other protective mechanisms, such as check sums, are not possible. The different
data groups can be separated by configurable characters.
The “ByteOrder” parameter is valid data transmission, although only the “LSB first” setting is
intended. The data item at the least significant address is transmitted first.
The UID, however, is always transmitted with “MSB first”, regardless of the “ByteOrder”
parameter.