pef80913 Infineon Technologies Corporation, pef80913 Datasheet - Page 141

• Manufacturer Part Number: pef80913
• Description: 2b1q Second Gen. Modular Isdn Nt
• Manufacturer: Infineon Technologies Corporation

3.2.3
For loopback #2 several alternatives exist. Both the type of loopback and the location
may vary. The following loopback types belong to the loopback-#2 category:
• complete loopback (B1,B2,D), in the U-transceiver
• complete loopback (B1,B2,D), in a downstream device
• B1-channel loopback, always performed in the U-transceiver
• B2-channel loopback, always performed in the U-transceiver
All loop variations performed by the U-transceiver are closed as near to the internal
IOM -2 interface as possible.
Normally loopback #2 is controlled by the exchange. The maintenance channel is used
for this purpose. All loopback functions are latched. This allows channel B1 and channel
B2 to be looped back simultaneously.
3.2.3.1
When receiving the request for a complete loopback, the U transceiver passes it on to
the downstream device, e.g. the S-bus transceiver. This is achieved by issuing the C/I-
code AIL in the “Transparent” state or C/I = ARL in states different than “Transparent”
(note: this holds true only for the EOC automode). The U transceiver may be
commanded to close the complete loopback itself.
Figure 65
•
Figure 65
The complete loopback is either opened under control of the exchange via the
maintenance channel or locally controlled via the µC. No reset is required for loopback
#2. The line stays active and is ready for data transmission.
Data Sheet
S-Transceiver
2B+D
illustrates the two options.
Loopback No.2
Complete Loopback
Complete Loopback Options in NT-Mode
loop request
Controller
127
loop command
U-Transceiver
2 B+D
Operational Description
loop command
PEF 82912/82913
U
lp2bymon8.vsd
2001-03-30