Operating Basics
20
GTS1063 and GTS1250 GBIC Test Systems Instruction Manual
A +5 V voltage or current overload in the GBIC receptacle is indicated on the
front panel. The status of these overload states is also available as TTL signals
on the rear panel. In addition, the absolute analog levels of both the GBIC
voltage and current loading can be monitored through buffered analog voltages
on a rear connector:
I Overload.
If a +5 V current overload exists in the GBIC receptacle (see
GBIC
Receptacle Supply Specifications starting on page 36), this rear-panel flag is high
(see figures 6 and 7) and the GBIC Test System shuts down the GBIC VDD
supply and makes the front-panel I Overload indicator blink. The GBIC Test
System turns the GBIC VDD +5V supply back on after the overload is removed
(such as uninstalling a shorted GBIC) and the GBIC Overload RESET button is
pressed or the REMOTE INTERFACE Overload RESET signal is pulsed low.
V Overload.
If a +5 V voltage overload exists (this is possible because of the
remote port V Offset input) in the GBIC receptacle, this rear-panel flag is high
and the GBIC Test System shuts down the GBIC VDD supply and makes the
front-panel V Overload indicator blink. The GBIC Test System turns the GBIC
VDD +5V supply back on after the overload is removed and the GBIC Overload
RESET button is pressed.
GBIC suppliers often guarantee Class I laser safety levels for the laser transmit-
ter output when an overvoltage from the GBIC host is prevented. The GBIC Test
System internal voltage regulator for the GBIC VDD supply and shutting down
the VDD supply on voltage or current overload protect the GBIC from voltage
overload.
Overload RESET (Active Low).
After a GBIC I or V Overload, you can turn the
+5 V VDD supply back on (assuming the overload condition is removed) by
either a power cycle, a front panel GBIC Overload RESET button press, or by
temporarily toggling this rear-panel signal low.
I Monitor.
An analog voltage representing the +5 V VDD current load of a GBIC
is available at the rear-panel I Monitor pin. This voltage is a linear function of
the current load in the GBIC Port Rece5 V Vdd supply. See Rear-Panel
Interface Connector Level Specifications on page 36 for the conversion gain
between the voltage output versus current flow. An operational amplifier buffers
this current-monitor signal through a 1 k
W
resistor (measure this signal using a
high impedance multimeter).
V Monitor.
An analog voltage representing the +5 V VDD being applied to the
GBIC is available at the rear-panel V Monitor signal pin. This is a direct
connection to the +5 V VDD supply at the GBIC receptacle port through a 1 K
W
resistor (measure this voltage using a high impedance multimeter).
GBIC Overload Flags and
Supply Monitor Signals
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