Measurement Computing Digital488/80A - Manual (Page 86)

With the power cord plugged in and connected to the Digital488/80A, turn on the unit by depressing the
rear-panel power switch. All of the front-panel LED indicators should light up for approximately one
second while the Digital488/80A performs an internal ROM and RAM self-check. At the end of this self-
check all of the LED indicators should turn off except for POWER.
Otherwise, the Digital488/80A may be in an error condition according to the one of the four following
LED patterns:
• If all of the LED indicators remain on: Then a ROM error has occurred.
• If the POWER LED indicator remains on while the rest of the LED indicators flash continuously:
Then a RAM error has occurred. Try cycling the power to the Digital488/80A to determine that the
error is repeatable.
• If the POWER and ERROR LED indicator remain on while the rest of the LED indicators are off:
Then a checksum error on Non-Volatile RAM occurred, and the saved configurations may be lost.
The checksum error condition may be cleared by doing a save of a configuration using the Save
Configuration (
S ) command.
Note: The error condition cannot be cleared by using the Query Error Status ( E? ) command.
• If all of the LED indicators are off: Then there may not be any power being supplied to the
Digital488/80A. In this event, check to make sure that the AC power cable is securely connected at
both ends. Otherwise, there may be a problem with the fuse. For more information, see section Power
Line & Fuse Configuration in Chapter 3.
Buffer Overrun
In Data Ready ( R ) mode R1 , the Digital488/80A waits for an EDR transition on the selected channel before
latching the data and formatting it for output. If the EDR line has changed state prior to being addressed to
Talk, the data read at the time of EDR is buffered for output when next addressed to Talk. If EDR changes
again before the previous EDR buffered data has been output, the Digital488/80A generates an Internal
Data Buffer Overrun (
E6 ) error and ignores the EDR read request. After output in the F0 through F4
formats, the Digital488/80A must be readdressed to Talk to perform subsequent buffered output of EDR
captured data.
In Data Ready ( R ) mode R2 , the Digital488/80A waits for an EDR transition on the selected channel before
latching the data and storing them in the internal data buffer. Up to 2000 readings may be latched and
stored. The EDR and Inhibit lines function in the same manner as in the
R1 mode. If an attempt is made to
store more than 2000 readings, the Digital488/80A generates an Internal Data Buffer Overrun ( E6 ) error.
After output in the F0 through F4 formats, the Digital488/80A must be readdressed to Talk to perform
subsequent buffered output of EDR captured data.
For more information, see the Data Ready ( R ) and Query Error Status ( E? ) commands in Chapter 6:
Digital488/80A Commands.
Query Error Status
The Query Error Status ( E? ) command is used to determine the present error condition on the selected
channel of the Digital488/80A. After execution of the E? command, the present error condition is cleared.
The error condition is also cleared by executing the User Status ( U ) command U0 . When an error has
occurred, the front-panel ERROR LED indicator turns on. The ERROR LED stays on until an E? or U0
command is executed.
If a Non-Volatile RAM Checksum Failure ( E5 ) occurs, then it can only be cleared by doing a save of the
configuration using the Save Configuration ( S ) command. Executing this command updates the checksum
to a known value and clears the E5 error condition.
For more information, see the Query Error Status ( E? ) and User Status ( U ) commands in Chapter 6:
Digital488/80A Commands.
80 Troubleshooting Digital488/80A User's Manual