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Addressing the Registers
To read or write to specific registers, you must use the register address.
Since the addresses for HP 75000 Series B or Series C plug-in modules are
A00 through A15, use the VME A16 mnemonic for the address space. The
address space within the mainframe/command module memory map
depends on the mainframe/command module used. For example, the address
of the HP E1300A/E1301A Mainframe starts at 1F0000
h
.
For the HP E1300/E1301, the A16 space is divided so modules are
addressed only at locations beginning with C000
h
within A16. Each
module is allocated 64 register addresses (40
h
). The module base address is
related to the logical address set by the logical address switch (LADDR) on
the module:
base address (
h
) = (logical address
h
)*40
h +
C000
h
For the RF multiplexers, the factory-set logical address is 120 (78
h
), so the
base address = (78
h
)*(40
h
) + C000
h
= DE00
h
. Then, for example, to address
the Status/Control register of an RF multiplexer in an HP E1300A/E1301A,
the register address = [A16 location]
h
+ [base address]
h
+ [register offset]
h
= 1F0000
h
+ DE00
h
+ 04
h
= 1FDE04
h
.
Reading the Registers
You can read the following RF multiplexer registers:
• ID register (base + 00
h
)
• Device Type register (base + 02
h
)
• Status/Control register (base + 04
h
)
• Bank 0 Channel Enable register (base + 08
h
)
• Bank 1 Channel Enable register (base + A
h
)
ID/Device Type
Registers
For either RF multiplexer, a read of the ID register (address base + 00
h
)
returns FFFF
h
since the multiplexers are manufactured by Hewlett-Packard
and are A16 only, register-based devices. The Device Type register (base +
02
h
) returns FF80
h
for the HP E1366A (50Ω) multiplexer and returns FF84
h
for the HP E1367A (75Ω) multiplexer.
Status/Control
Register
Each relay requires about 15 msec execution time (close to open or open to
close) during which time the RF multiplexers are “busy”. A read of the
Status/Control register (base + 04
h
) returns FFFF
h
when the module is not
busy or returns FF7F
h
(bit 7 is low-true) when the module is busy.
Channel Enable
Registers
A read of either of the two Channel Enable registers (base + 08
h
for bank 0
or base + A
h
for bank 1) always returns FFFF
h
, regardless of the channel
states.
66 HP E1366A/E1367A Multiplexer Registers Appendix B