Appendix E: Performance Verification
VX4801 Programmable Digital I/O Module A–31
This test sequence verifies that data can be transferred to and from the VX4801
using the four handshake signal lines Data Ready (DRD), Data Acknowledge
(DAK), Ready for Data (RFD), and Data Available (DAV).
NOTE. Typing errors will result in a VX4801 error condition which must be
cleared before subsequent commands will be recognized. If at any time you
suspect that an error condition exists, send an error query and read the result
before continuing with the test sequence ibwrt “qa” <cr>, ibrd 100 <cr>.
Equipment
Requirements Loop-back assembly (item 3)
Prerequisites All prerequisites listed on page A–20
1. Connect the loop-back assembly as shown in figure 4.
2. Using the following steps, verify a data byte transfer 55 hexadecimal from
the VX4801 (byte 5) to the Slave (byte 3) using the Ready for Data (RFD)
from the Slave and the Data Valid (DAV) from the VX4801:
a. Set the VX4801 for a positive edge handshake, to update the output data
on receipt of a Ready For Data (RFD) strobe, to update the input data on
receipt of a Data Ready (DRD) strobe, and for byte 5 to be an active high
output, initialized with a Load Output data value of 55 hexadecimal and
with its tri-state inactive:
!
$! "!
b. Set the Slave mode for byte 2 to be an active high output (for assertion
of RFD), for bytes 1 and 3 to be active high inputs (byte 1 to detect DAV
and byte 3 to input data), and for all tri-states to be inactive:
! #
$! !
c. Set the Slave to input byte 1 (with all bits masked except bit 1) and
byte 3 and verify that DAV is un-asserted (i.e. byte 1, bit 0 = 0) and
consequently, that there is no data (byte 3 = 00):
$!
(Observe: 0000 and VX4801 DAV light off)
Check Handshake