Digi 90031300 manual Alarms on a T1 Span, T1 Modem Bank Interaction

Alarms on a T1 Span

Alarm	Reason for Alarm	Result of Alarm
Red	The T1 Modem Bank is not receiving a valid signal	The T1 Modem Bank sends a “Yellow
Alarm	from the T1 Line.	Alarm” down the T1 line, and it will not
		accept calls or dial out.
Yellow	The Central Office was in a Red Alarm state (i.e., it	The T1 Modem Bank can not accept
Alarm	can’t hear you). The alarm goes away	calls or dial out on the T1 line.
	approximately 15 seconds after the Red Alarm
	clears itself.
Blue	Keep-alive signal from the T1 Line. Remote CSU is	The T1 Modem Bank can not accept
Alarm	generating it, or an improper supervision mode	calls or dial out on the T1 line.
	(signaling) was chosen.

T1 Modem Bank Interaction

Interaction takes place between the PSTN, the T1 Modem Bank, and the PC containing the EPC/X host adapter.

Figure 29 shows the major components of the T1 Modem Bank and the connections between them. An EPC sync link interconnects an EPC/X host adapter and an EPC concentrator. (The EPC/X host adapter plugs into a slot in a computer’s interface bus.) Data is then transmitted via V.34 modems to a T1 Line interface, which in turn sends the data to the T1 line. This occurs using a T1 line in either CSU mode or non-CSU DSX-1 mode.

∙CSU mode can transmit data on a T1 line over distances from 0 to 6,000 feet, without a repeater, using 22 AWG twisted-pair cable.

∙Non-CSUDSX-1 mode transmits to a PBX only over short distances, up to 655 feet, with receive jitter attenuation.

Figure 29 Functional Block Diagram of the T1 Modem Bank

78 T1 Modem Bank