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Chapter 3 - General Operation
34 Adept IO Blox User’s Guide, Rev B
3.6 IO Blox LEDs
There are two surface-mount style LEDs on the IO Blox: a green STATUS LED and a red
OVRTMP LED. See Table 3-3 for descriptions.
An OVRTMP indication is the result of an over-temperature or over-current condition on
one or more of the outputs, usually due to a short-circuit condition. As a result, the output
driver IC will oscillate on and off as the chip tries to drive the load. The LED will turn on
and off along with this temperature cycling characteristic.
The red OVRTMP LED is active only when:
• An output has been turned on by a V+ command and:
a. One or more activated outputs has a thermal overload problem, usually due
to a short in the user's wiring from the output pin to the user's ground.
OR
b. Total current drawn by all active outputs has exceeded the case temperature
rating over time. See the Total Current Limitation, all channels on entry in
Table 3-2 on page 32 .
Table 3-3. IO Blox LED Condition Descriptions
Green STATUS LED On steady = logic power on, no communication
On blinking = communication with host OK
Off = no logic power
Red OVRTMP LED On = over-temperature condition in the output driver
IC. The OVRTMP LED is the only driver error
indication, there is no software feedback of this
condition.
Off = outputs OK