Operating Basics
2–2 VX4380 256-Crosspoint Relay Matrix Module User Manual
Instrument I/O: VXIbus Basics
NOTE. If the user’s mainframe has other manufacturers’ computer boards
operating in the role of VXIbus foreign devices, the assertion of BERR* (as
defined by the VXIbus Specification) may cause operating problems on these
boards.
The Option 01 Module installed on a switching module is a C-size single slot
VXIbus Message-Based Word Serial instrument. It uses the A16, D16 VME
interface available on the backplane P1 connector and does not require any A24
or A32 address space. The module is a D16 interrupter.
The Option 01 is neither a VXIbus commander nor a VMEbus master; therefore
it does not have a VXIbus Signal register. The Option 01 is a VXIbus message-
based servant.
The module supports the Normal Transfer Mode of the VXIbus using the Write
Ready, Read Ready, Data In Ready (DIR), and Data Out Ready (DOR) bits of
the module Response register.
A Normal Transfer Mode read of the Option 01 proceeds as follows:
1. The commander reads the Option 01 Response register and checks if the
Write Ready and DOR bits are true. If they are, the commander proceeds to
the next step. If not, the commander continues to poll these bits until they
become true.
2. The commander writes the Byte Request command (hexadecimal 0DEFF) to
the Data Low register of the Option 01.
3. The commander reads the Option 01 Response register and checks if the
Read Ready and DOR bits are true. If they are, the commander proceeds to
the next step. If not, the commander continues to poll these bits until they
become true.
4. The commander reads the Option 01 Data Low register.
A Normal Transfer Mode write to the Option 01 proceeds as follows:
1. The commander reads the Option 01 Response register and checks if the
Write Ready and DIR bits are true. If they are, the commander proceeds to
the next step. If not, the commander continues to poll the Write Ready and
DIR bits until they are true.
2. The commander writes the Byte Available command which contains the data
(hexadecimal 0BCXX or 0BDXX, depending on the End bit) to the Data
Low register of the Option 01.