Measurement Computing DAC488 v.1 - Manual (Page 19)

DAC488 User’s Manual DAC488 Power & Assembly 13
DAC488 Power & Assembly 3
Introduction…… 13
Internal Components…… 13
Factory Service…… 13
Power Line & Fuse Configuration…… 14
Line Voltage Selection…… 14
To Select the Line Voltage…… 15
Fuse Replacement…… 16
To Replace the Fuse…… 16
Rack-Mount & Bench-Top Assembly…… 17
Rack Mount…… 17
Bench Top…… 17
Power-Up & Performance Tests…… 18
Power-Up Activation…… 18
Programming Examples……19
KYBDCTRL.BAS Program…… 19
To Run the Keyboard Controller Program…… 19
DAC488 Command Responses…… 20
Performance Verification…… 20
To Verify the Port Voltage - 10-Volt Range…… 21
To Verify the Port Voltage - 5-Volt Range…… 21
To Verify the Port Voltage - 1-Volt Range…… 22
Data Transfer Speeds…… 22
Introduction
Internal Components
The heart of the DAC488 is a 6809 microprocessor [U101] supported by 16K bytes of firmware EPROM
[U102] and 32K bytes of battery-backed-up RAM [U103]. Interface to the IEEE 488 bus is accomplished
by a 9914 interface chip [U105]. A 65C22 [U109] generates real-time interrupts for the firmware operating
system and also drives the front panel LED indicators.
Isolation of the analog ports is accomplished using separate bipolar power supplies for each port. Opto-
Isolators are used to isolate the digital and analog circuitry. High voltage/high current output capability is
available on the digital output port through a 74HCTLS240 and a ULN2803A peripheral driver [U144].
Calibration of the analog ports through program control is accomplished by the use of two 8-bit D/A
converters on each analog circuit. One converter is used to adjust the gain and the other converter to adjust
the offset.
Factory Service
Chapter 8 provides a troubleshooting reference for possible solutions to technical problems. Before calling
for technical assistance, refer to this chapter.
However, if problems in using the DAC488 still persist, you should contact the factory. Many problems
can be resolved by discussing the problems with the appropriate applications department. If the problem
cannot be solved by this method, you will be instructed as to the proper return procedure.