User`s manual

82 16-Channel Relay Multiplexer Registers Appendix B
Writing to the
Registers
You can write to the following multiplexer registers:
-- Status Control Register (base +04
16
)
-- Tree Switch Registers (base +06
16
)
-- Channel Registers (base +08
16
)
Status Control Register 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 occurring. A backplane
interrupt always occurs after a channel write.
Tree Switches and
Channel Registers
Writing a "1" to these registers closes the channel/tree switch and writing a
"0" opens the channel/tree switch.
Resetting the Module 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 does not indicate when the relays have
settled.
Changing Channels 1. Write to the Tree Switch and Channel Registers.
2. Wait for busy to go to "1" or for a backplane interrupt.