HGLM-1063 Ver la hoja de datos (PDF) - HP => Agilent Technologies

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HGLM-1063

Fibre Channel GBaud Optical Link Module

HP => Agilent Technologies 

6. After holding -Lock to

Reference low for 500 µsec it

should then be driven high. This

causes the module to phase and

frequency lock onto the incoming

data stream within 2500 bit times

(2.4 µsec).

7. After 2500 bit times, the

modules should be in bit syn-

chronization, but not yet byte

synchronization. The Receive

Byte Clock (RBC0) should be

running at 53.125 MHz.

8. Finally, drive the data lines

Tx[00:19] with a K28.5 (comma

or byte sync) character. Upon

detection of this character, the

receiver will drive the Comma

Detect line high, the clocks will

align to the byte boundary, and

the receive data lines (Rx[00:19])

will have valid data. The link is

now ready for data transmission.

TX_SI Operation

In normal operation, pin Tx_SI

should be held low. In this mode,

the data at Tx[00:19] is serialized

and driven over the fiber optic

link. With pin Tx_SI driven high,

however, the data at Tx[00:19] is

serialized and driven out the

± Serial Data Out lines and the

data applied to the ± Serial Data

In lines are driven over the fiber

optic link.

EWRAP Operation

To aid in link diagnostics, the

modules have the capability of

wrapping the local transmit data

electrically back to the local

deserializer. This feature is

enabled by driving the EWRAP

pin high. When enabled, EWRAP

causes the laser to turn off within

20 µsec. The OFC circuit goes

into its low duty cycle “on-off-on”

handshake mode. The link will

need to be stepped through the

synchronization procedure

outlined above to return to

normal operation after EWRAP is

brought low.

Enable Comma Detect

In the synchronization procedure

above, the Enable Comma Detect

(EN_CDET) signal is driven high

to allow the receiver to reset and

align its boundaries properly

when a K28.5 character is

transmitted. This line can be kept

in a high state and the receiver

will reset on every K28.5

character it detects. This feature

can be disabled, after initial

synchronization, by driving

Enable Comma Detect to a low

state.

Open Fiber Control

The purpose of the Open Fiber

Control (OFC) integrated circuit

is to ensure user safety. This

circuit uses the dual loss of light

signals from the receiver I.C. and

the laser Fault detection signal

from the transmitter I.C. to

determine if the laser and the

fiber link are properly connected

and functioning normally. Should

a Fault condition be determined,

all laser transmission is shut

down.

A safety interlock is provided by

the HGLM-1063 module. HGLM-

1063 modules (or equivalent)

must be connected in full point-

to-point configuration as shown

in Figure 3 for proper operation.

The Open Fiber Control System

(OFCS) of the HGLM-1063

deactivates the laser signal

whenever there is an interruption

or loss of signal of either laser

drive circuit.

For example, in Figure 3, if Path

A is opened through a cut or

other physical damage to the

fiber, or if the fiber is discon-

nected at either the transmitting

port of HGLM1 or the receiving

port of HGLM2, the OFCS detects

the loss of signal. The Link

Unusable line of HGLM2 goes

high, signaling the system of an

open fiber condition. The OFCS

then shuts down the laser of

HGLM2. HGLM1 in turn detects

this loss of signal, raises its Link

Unusable line, and shuts down its

laser. The OFC pulses the laser of

HGLM2 at a very low duty cycle.

Simultaneously, the OFCS of

HGLM1 detects the low duty

cycle operation of HGLM2 and

places its laser in the same low

duty cycle pulsing mode. It takes

less than 2 msec to shut down all

laser transmission and results in a

safe (Class I) laser emission level

in Path A, the open path.

While Path A is still open,

HGLM1 launches a pulse

synchronously with the pulse it

receives on Path B from HGLM2.

However, HGLM2 receives no

pulse (because Path A is open)

and continues in an inactive

mode. HGLM2 will continue

launching “inquiry” pulses once

approximately every 10.1 seconds

along Path B.

After Path A is restored, HGLM2

will receive pulses along Path A,

synchronous with its transmit

pulses along Path B. A completed

link of Path A and Path B is

verified by both HGLM1 and

HGLM2. HGLM2 will verify its

link by deactivating its laser and

confirm that its receive signal

disappears. HGLM1 also

performs the same verification

check, deactivating its laser.

Once both HGLM modules have

729

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