PEB2085 SIEMENS [Siemens Semiconductor Group], PEB2085 Datasheet - Page 127

• Manufacturer Part Number: PEB2085
• Description: ISDN SubscribernAccess Controller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Reaction of the ISAC-S
In the following various possible actions to be taken according to § 5.8.5 parts a) through c)
are discussed separately.
Semiconductor Group
a) There are different types of undefined frames:
b) If the length of the frame is too small 1.1.1b) applies and the frame is invalid. Therefore
c) An invalid N(R) is one that does not meet the condition
incorrect length can only mean:
1) I-frame which is not command
2) S-frame with bits 8-5 in Octet 4 = 0 an ISTA: PCE-interrupt is generated
3) A-frame with bits 4-1 in octet 4
4) Frame with bits 2-1 in octet 4 equal
5) SABME, UI, DISC, not a command,
1) S-frame with more than 6 octets
2) Undefined frames with 5 octets,
3) SABME, BM, DISC, UA-frame
4) A FRMR with not exactly 10 octets After a RME and identifying FRMR by
This condition is automatically checked within the device and in the case of an invalid
N(R) an ISTA:PCE-interrupt is generated. An S-field response is done by the ISAC-S
in all prescribed cases of invalid N(R) automatically.
equal to "1101" (selective reject)
to "11" but control field not contained
in ISTA: RME interrupt;
DM, UA, FRMR not a response
ISTA: RME interrupt;
bits 2-1 in octet 4 not being equal
to "11" (e.g. modulo 8 S-frame)
with more than 5 octets
V(A) < N(R) < V(S)
127
an ISTA: PCE-interrupt is generated
an ISTA: PCE is generated
the control field can be read afterwards in
RHCR (after having checked for invalid
frame condition).
the control field can be read afterwards in
RHCR, the C/R-bit in the SAPR-register
(after having checked for invalid frame
condition).
an ISTA:PCE-interrupt is generated; the
contents of the additional octets is discarded.
an ISTA:PCE-interrupt is generated
after ISTA:
RME and identifying the frame by RHCR the
RSTA:RDA bit is 1 if the frames had more
than 5 octets and 0 if they had exactly 5 octets.
reading RHCR-register, the software has to
read RBCH, RBCL. If OV = 1 or
RBC11-RBC0 = 0 … 101 then the FRMR did
not have exactly 10 octets.
Functional Description