OBID
®
System-Manual
ID RW40.30-USB
FEIG ELECTRONIC GmbH
Page 12 of 57
H80701-2e-ID-B.doc
2.4. Data Format and Protocol Frames for bi-directional communication
The communication between Reader and connected host (terminal, PC, etc.) is executed by means of
fixed protocols. The used protocol is intended for data bus use and is equipped with an individual bus
address for each device.
During data transfer the Reader supplies the required data or a status byte. The reply contains the
transmitted command byte.
There is no reply from the Reader in case of a protocol frame failure.
The Reader supports two different Protocol frames which are the standard and the advanced protocol
frame. The Host Application has to chose protocol frame as described in this manual.
2.4.1. Standard Protocol Frame
Host
→
Reader
1
2
3
4...n-1
n
LENGTH =
n
COM-ADR
COMMAND
(DATA)
CSUM
Host
←
Reader
1
2
3
4
(5...n-1)
n
LENGTH
(n)
COM-ADR
COMMAND
STATUS
(DATA)
CSUM
2.4.2. Advanced Protocol Frame
Reader
←
Host
1
2
3
4
5
(6...n-2)
STX
(0x02)
MSB
ALENGTH
LSB
ALENGTH
COM-ADR
COMMAND
(DATA)
©
n-1
n
ª
LSB
CRC16
MSB
CRC16
Host
←
Reader
1
2
3
4
5
6
(7...n-2)
STX
(0x02)
MSB
ALENGTH
LSB
ALENGTH
COM-ADR
CONTROL-
BYTE
STATUS
(DATA)
©
n-1
n
ª
LSB
CRC16
MSB
CRC16