psb21391 Infineon Technologies Corporation, psb21391 Datasheet - Page 76

• Manufacturer Part Number: psb21391
• Description: Siemens Codec With Upn Transceiver
• Manufacturer: Infineon Technologies Corporation

Data Sheet
2.3.4.3
The A/B bit has been added to the IOM-2 frame for the operation of a S/T-terminal
adapter based on the SBCX PEB 2081. It is used to transfer the state of the line card
HDLC controller indicated by the U
If the A/B bit is ’1’, it indicates that the line card HDLC controller is available and D-
channel messages may be transmitted. If it changes to ’0’ the HDLC controller has to
abort the transmission and has to restart the transmission after the A/B bit becomes ’1’
again.
The A/B bit is used by the SBCX on a S/T interface option to control the ECHO channel
of the S/T interface and the Stop/Go bit on the IOM-2 interface.
2.3.4.4
The layer-1 (U
to either the S/G-bit position or the A/B-bit position according to the TCM bit in the
TR_CONF0 register. The bit polarities are as follows:
Downstream (U
T-to A/B-mapping (TCM = ’1’):
T-to S/G-mapping (TCM = ’0’):
Upstream (IOM
The T-channel in upstream direction is controlled by the BAC-bit of the IOM-2 interface.
The T-channel transmits the inverse of the BAC-bit.
Special care is taken so that the slave terminal will only send one HDLC-frame until the
TlC-bus of the master IOM-2 interface is released. This is achieved by a circuitry which
latches the BAC-state of ‘1’ until at least one T-bit has been transmitted with the value of
‘0’ which releases the TlC-bus of the master IOM-2 interface.
BAC to T-mapping:
Available/Busy Bit
T-Bit Transfer
PN
PN
) part of the SCOUT-P(X) conveys the T-bit position of the U
U
PN
IOM)
T = 0:
T = 1:
T = 0:
T = 1:
BAC = 1
BAC = 0
)
PN
A/B = 0 S/G = 1 blocked
A/B = 1 S/G = 1 available
A/B = 1 S/G = 1 blocked
A/B = 1 S/G = 0 available
T = 0
T = 1
T-channel to the SBCX.
66
no D-channel request
D-channel request
PSB 21391
PSB 21393
PN
Interfaces
2001-03-07
interface