SAB 82525
SAB 82526
SAF 82525
SAF 82526
Receive Status Register (READ)
7
0
RSTA
VFR
RDO
CRC
RAB
HA1
HA0
C/R
LA
(27/67)
VFR … Valid Frame
Determines whether a valid frame has been received.
1 … Valid
0 … Invalid
An invalid frame is either
– a frame which is not an integer number of 8 bits (n × 8 bits) in length (e.g. 25 bit), or
–
a frame which is too short depending on the selected operation mode via MODE (MDS1,
MDS0, ADM) as follows:
Auto-/non-auto mode (16-bit address): 4 bytes
Auto-/non-auto mode (8-bit address): 3 bytes
Transparent mode 1:3 bytes.
Transparent mode 0:2 bytes.
Note: Shorter frames are not reported.
RDO … Receive Data Overflow
A data overflow has occurred within the actual frame.
Caution: Data loss because the CPU did not serve RME or RPF interrupt in time.
CRC … CRC compare/check
0 … CRC check failed; received frame contains errors.
1 … CRC check o.k.; received frame is error-free.
RAB … Receive Message Aborted
The received frame was aborted from the transmitting station.
According to the HDLC protocol, this frame must be discarded by the CPU.
Semiconductor Group
95
SIEMENS [ Siemens Semiconductor Group ]
