VXI SM8000 - Manual (Page 36)

VXI Technology, Inc.
36 SM8000 Series Operation
BUSY Signal
The BUSY bit is driven high by the device whenever a Set Attenuation command is received, or
when a RESET signal is received. The BUSY signal remains high whenever a command is
executed and the stepper motor is moving. During this time, no other commands should be sent to
the device, as this may corrupt the internal state of the device requiring a RESET to clear.
ERROR Status
The ERROR bit is driven high by the device whenever an Out of Range error, or a RESET error is
detected. RESET errors occur when the unit does not find its Park position correctly, and may
indicate a hardware problem.
Resetting the Device
See the RESET commands in the Programming section.
Commanding the Devices
Step 1 - Power Up and Initialize
The device will reset when power is applied.
Step 2 - Query Default Parameters
Before using the device in calibrated mode, query to obtain the minimum and maximum absolute
attenuation. Use this data to ensure that commands sent are always within range. The commands
to gather the device information are:
• Query Minimum Attenuation - 82h
• Query Maximum Attenuation - 83h
Step 3 - Actuate the Device
Use the appropriate Set commands and actuate the device. For verification purposes, pick a large
change first to ensure proper operation of the device. Very small changes can be requested,
however, they can be misleading for test purposes since they are practically undetectable. The
command to actuate the device is:
• Set Attenuation - 80h