Rockwell Automation 1771-OFE/B Analog Output Module User Manual - Manual (Page 66)

7-2
Publication 1771Ć6.5.30 - November 1998
Table 7.A
Troubleshooting Chart
Condition Possible Cause Recommended Action
Green RUN indicator does not
come on.
No Power to Module
Bad internal fuse
• Check I/O chassis for power.
• Turn off power to I/O chassis. Remove
and reinsert module into chassis. Return
power to I/O chassis.
Red FAULT indicator is on
continuously with the
processor in program and
run modes.
Unsuccessful PowerĆUp
• EPROM Fault
• Checksum Error
• Cycle power.
• Replace faulty module if necessary.
Block transfers are not being
performed.
• Block Transfer
Instructions Programmed
Incorrectly
• Module has failed
selfĆdiagnostics.
• Check user program .
• Cycle power.
• Replace faulty module if necessary.
The module allows a five-word read block transfer for rudimentary
program or hardware debugging (Figure 7.2). If a read block
transfer request is for more or less than five words, the module will
not perform a read block transfer.
Figure 7.2
Word Assignment for Read Block Transfer
Decimal Bit 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Octal Bit 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
Word 1 Channel 1 DAC Input Data
2 Channel 2 DAC Input Data
3 Channel 3 DAC Input Data
4 Channel 4 DAC Input Data
5
Not
used
I/O
Reset
Reserved Data Valid
Important: The user program that utilizes the read block transfer
must make sure that bits 06 and 07 (the write enable
and read enable request bits) of the MCB are not set
simultaneously.
The first four words of the read block transfer show the actual 12 bits
of data sent to the module’s digital-to-analog converters (DACs).
The first four words in the read block transfer appear in 12-bit binary
format regardless of the module’s mode of operation (BCD or 12-bit
binary).
Read Block Transfer
Status Words