Toshiba CTX28 manual RDTU1 and 2 LED Functions Alarm LED, Falm, Mfalm, Yalm, Psync/Ssync

T1

RDTU1 & 2 - T1 Interface Unit

Alarms are used to indicate potentially serious telephone network problems. Example: when monitoring a T1 network, if a Blue or Yellow alarm is indicated, it can be concluded that there is a cable fault or some other serious transmission impairment.

Table 8-12 RDTU1 and 2 LED Functions
	Alarm LED	Function
	Frame Alarm	Turns On steady if the RDTU has not achieved synchronization or when the span
	(FALM)	cable is not connected.
		LEDs turn On steady if the RDTU receives the 1.554 mbs T1 carrier from the far
	Multi-Frame Alarm	end, but has not achieved Frame synchronization or when the span cable is not
	(MFALM)	connected. Also, if the RDTU is set for SF and the far end is sending ESF (or vice
		versa), the MFALM LED will be On steady.
		When FALM and MFALM are both On steady, it’s a Red alarm condition. This	T1
	Red Alarm (FALM	means the RDTU does not detect a proper carrier signal (1.544 mbs T1) on its
		receive pair and the RDTU is not synchronized. During a Red alarm condition, the
	and MFALM)
		RDTU turns the BSY LED On steady and attempts to send a Yellow alarm signal
		(RDTU YALM LED flashes) to the far end T1 circuit.
		When the far end network or CPE T1 does not detect the RDTU transmitted 1.544
		mbs T1 carrier signal on its receive pair the far end, T1 sends a Yellow alarm signal
	Yellow Alarm	pattern to the RDTU. The RDTU should turn on the YALM LED (the YALM repeats
	(YALM)	the signal it receives from the far end—flashing or steady). If the RDTU does not
		receive the far end carrier signal, the RDTU sends the Yellow alarm signal to the far
		end and causes the BSY and YALM LEDs to flash.
		The Blue alarm, also known as the Alarm Indication Signal (AIS), is detected by the
		RDTU. This signal is sent by the Far End Network equipment to RDTU when it
		loses the carrier from a Network T1 circuit (other than RDTU). This signal assures
	Blue Alarm (BALM)	that the RDTU maintains synchronization when there is a problem between two
		Network Nodes. The RDTU BALM also lights if the far end sends a Blue alarm
		signal during loop back. The RDTU sends a Blue alarm signal when loop-back test
		is being performed.
		See Figure 8-6 on page 8-16– If one RDTU PCB is assigned as the Primary Timing
		T1 PCB in Program 105, the PSYNC LED of this RDTU PCB flashes when it is
		synchronized with the far end T1 span line clock provider.
	Primary	If the Primary RDTU is not synchronized with the clock provider, the PSYNC LED
	Synchronization	will be On steady. The SSYNC LED of the Primary sync RDTU PCB should always
	(PSYNC)	be Off. The Primary sync RDTU PCB synchronizes the RTCU (time-switch) to the
		clock signal it receives from the T1 span circuit to which it is connected. The RTCU
		then synchronizes the Strata CTX PCM talk path (time-switch) to the far end PCM
		talk path.
		If an RDTU PCB is assigned as the Secondary time T1 PCB in Program 105, its
		SSYNC LED will be On steady (standby mode) when the Strata CTX is
		synchronized to the Primary T1 clock provider.
	Secondary	In the event Primary synchronization is lost (4 out of 12 consecutive frame timing
	Synchronization	bits are in error), the Strata CTX switches from synchronizing to the Primary RDTU
	(SSYNC)	span line clock to the span line clock connected RDTU designated as the
		Secondary Timing Reference. When the Strata CTX is synchronized to the
		Secondary Reference RDTU, the PSYNC LED on the Primary Reference RDTU
		turns on steady and the SSYNC LED on the Secondary Reference RDTU will flash.
	Run Free	If the RDTU PCB is the clock provider to the Far-end T1 span circuit, both the
	(PSYNC/SSYNC)	PSYNC and SSYNC LEDs are always Off.

Strata CTX I&M 06/04 8-17