Writing To The Registers - HP E1346A User Manual

Writing to the
Registers
Status Control Register
Tree Switches and
Channel Registers
Resetting the Module
Changing Channels
68 HP E1346A Multiplexer Registers
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You can write to the following multiplexer registers:
•
Status Register (base +04
•
Tree Switch Registers (base +06
•
Channel Registers (base +08
Writing a "1" to bit 0 of this register resets the interface circuitry to its
power-on state and opens all channels. This is the only allowable write to
this register.
Bit 7 is the only bit that has meaning when reading this register. The busy
bit will go true for about 1 msec after a write to either the Tree Switch
Register or the Channel Registers. The transition of the busy bit from
"busy" to "not busy" corresponds to a backplane interrupt occuring. A
backplane interrupt always occurs after a channel write.
Writing a "1" to these registers closes the channel/tree switch and writing a
"0" opens the channel/tree switch.
To reset the module:
1. Write a "1" to bit 0 of the Status Control Register
2. Wait 100 usec
3. Write a "0" to bit 0 of the Status Control Register
NOTE: The busy bit in this case doesn't indicate when the relays have
settled.
1. Write to the Tree Switch and Channel Registers.
2. Wait for busy to go to "1" or for a backplane interrupt.
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Appendix B