VXI SM8000 - Manual (Page 34)

VXI Technology, Inc.
34 SM8000 Series Operation
SM8003 - Prism Switches
When controlling single mode prism switches the operation of the SM8000 is also similar to that
of any other SMIP II family product. The switches are directly controlled by register writes to the
Relay Register. See Writing to the Relay Register in the Programming section for a detailed
explanation of this type of operation. Only relay register 00h is used to control the prism switches.
SM8101 / SM8102 - Optical Attenuators
The attenuator modules are internally controlled via an I 2 C bus interface. Operation of this type of
module is accomplished by loading the proper command and attenuator data information into the
proper registers inside the SM8000.
The SM8000 must be configured to control the attenuator modules on one of four ports. These
same ports are used for the multi-switch devices. This is done at the factory with hardware
selectable jumpers. Once configured for attenuator module operation, the control of the attenuator
module consists of writing the control word and the attenuator data word to the SM8000. This
operation is more fully discussed in the Programming section of this manual.
Once the Relay Register (02 through 08) has been configured to control an attenuator, and has
been written to, the command sequence is initiated and the module begins to move to the newly
commanded setting. The Busy signal from the optical module may be monitored to indicate when
the optical module has finished moving to the commanded attenuation. The optical module also
generates an Error signal that may be monitored. This signal might be used to provide a
confidence check that the module is being controlled properly.