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Addressing the Registers
To read or write to specific registers, you must use the register address.
Register addresses for HP 75000 Series C plug-in modules are in address
space VXI A
16
. The locatio
n
of A16 within the mainframe/command
module memory map depends on the mainframe/command module used.
For example, the A16 location of the HP E1300/E1301 Mainframe starts at
1F0000
16
(
16
= HEX).
The A16 space is divided so modules are addressed only at locations
beginning with C000
16
within A16. Allocated for each module are 64
register addresses (40
16
). The module base address is related to the logical
address set by the module’s logical address switch (LADDR). The module
address is:
module address
16
= (logical address
16
) * 40
16
+ C000
16
For the Microwave Switch modules, the default logical address is 120
(78
16
), thus the module address within A16=
78
16
* 40
16
+ C000
16
= DE00
16
For example, to address the Status/Control Register of a Microwave Switch
module in an HP E1300/E1301 Mainframe, the command register address is:
[A16 location]
16
+ [module address]
16
+ [register offset]
16
=
1f000
16
+ DE00
16
+ 04
16
= 1FDE04
16
Reading the Registers
You can read the following Microwave Switch registers:
• Manufacturer ID Register (base + 00
16
)
• Device Type Register (base + 02
16
)
• Status/Control Register (base + 08
16
)
• Channel Enable Register (base + 08
16
)
ID and Device Type
Registers
ID Register: Reading the register returns: FFFF
16
. This shows
Hewlett-Packard as the manufacturer and that the module is an A16
register-based device.
Device Type Register: Reading this register returns FF28
16
if the device is
either the E1368A Microwave Switch module, or the E1369A Microwave
Switch Driver module.
76 HP E1368A/69A/70A Registers Appendix B