Agilent Technologies 5517B Operation And Service Manual page 36

• The REFERENCE LED will be extinguished until the HP 5517B is ready for use.
• HOWEVER, FOR SYSTEMS WITH MULTIPLE HP 10760A CARDS
• Every ODD HP 10760A that uses the replicated REF and -REF will have their REFERENCE LED lit during
the laser head warmup period. (This is due to inversion in the replication circuitry.) Note that this does not
apply to multiple HP 10764C card installations.
• The MEASUREMENT LED will momentarily light several times during the laser head warmup period
provided that the HP 10780B Receiver is aligned properly with the beam. (This occurs because the laser
periodically produces functional optical frequencies during warmup.)
NOTE
THE ABOVE MONITORING SCHEME ASSUMES NO REVERSAL OF THE REF AND - REF LINES IN THE
CABLING.
3-14. Systems with HP 10745A or HP 10746A Cards - Automatic Monitoring
3-15. Systems with these cards can use the system computer and software to monitor the laser head warmup. Before
describing the software, it will be helpful to examine some background information on the HP 10740A Coupler, HP
10745A HP-IB Interface, and HP 10746A Binary Interface.
3-16. HP 10740A Coupler - Error Signal Information
• Four error signal lines are provided on the HP 10740A Backplane:
- REFERENCE ERROR BIT
- MEASUREMENT ERROR BIT
- V.O.L. ERROR BIT
- OVFL BIT
3-17. HP 10746A Error Signal Processing
• If any of the HP 10740A backplane error bits are true, the four most significant bits of the most significant
word in a data transfer from the HP 10746A to the host computer will be all ones. These four bits are
normally the decimal point bits.
• Errors are not the only condition that can set these bits to all ones. When the difference output of an
addressed HP 10762B is within tolerance, these bits will also be set.
• After detecting all ones, the host computer must check the next four MSB's to differentiate between an error
condition and the within tolerance condition.
• If the tolerance condition is true, these next four bits will also be all ones. Otherwise, each of these bits
corresponds to one of the backplane error bits.
3-18. HP 10745A Background Information
• When a backplane error bit is true, the HP 10745A asserts SRQ. The STATUS BYTE of the HP 10745A can be
read to determine the source of SRQ. In the STATUS BYTE, bit 0 corresponds to the REFERENCE ERROR-BIT.
3-19. Program Modifications
3-20. To monitor warmup time, the following program modifications can be added to the example programs
Tables 4-12 and 4-13
contained in
Number 05501-90028). If desired, some form of time-out algorithm can be added to check if the HP 5517B warms up
within 10 minutes.
of the HP 5501A Laser Transducer Operating and Service Manual (HP Part