Siemens SIMATIC TIWAY 1 - Manual (Page 197)

USING THE BDLC PROTOCOL
UNILINK HOST ADAPTER B–12
USER MANUAL
B.5.7 FRMR Recovery
The FRMR response is returned by the adapter when it receives a frame with an
invalid command, a frame of excessive length, or when the N(R) does not match.
This response includes a three-byte information field in the format shown in
Figure B–5, with Byte 0 transmitted first.
Rejected Control Field
0 0 N(R)
W
0 1 2 3 4 5 6 7
MSB LSB
N(S)
X Z
First bit transmitted
Byte 0
Byte 1
Byte 2 Y 0 0 0 0
Figure B–5 FRMR Information Field Format
The Rejected Control Field is the control field from the command frame that is
being rejected.
N(R) is the adapter’s current receive count.
N(S) is the adapter’s current send count.
Bit Z is set to one when the control field in the frame received contained an
invalid N(R) number.
Bit Y is set to one when the information field received exceeds the maximum
length of 290 bytes.
Bit X is set to one when the control field in the frame received is invalid because
the frame contained an information field and the control field command does
not permit an information field.
Bit W is set to one when the control field in the frame received is invalid or not
implemented.