IBM Series 1 User Manual page 164

c
c
Each DI group can
non-interrupting, (2)
and (4) diagnostic.
ope rat e i non e
0
f f
0
u r mod e s ; ( 1 )
process interrupt, (3) external sync,
Non-In terr uptilHI Mogg.
When
operated in the non- interr upting
mode, the state of the
Dr
group non-latching input register
is read with the Read 01 command. The Read PI command reads
the history of the 01 inputs from the latching PI register.
This PI register records the first logical "zero" to logical
"one" transition of each
Dr
input following any system or
feature reset. The Read
PI
with Reset command reads the PI
latching register and resets it at the end of the
instruction cycle.
Pro~.§.§ I.!!1~!..£..!!£1
Mode. The process interrupt mode is
entered by performing the Arre PI command. The first logical
"zero" to logical "one" transition on any input of the armed
group sets the appropriate bit in the latching register and
causes an interrupt to be posted to the channel. After the
interrupt is serviced, a Read PI with Reset command reads
the latching register and resets it, allowing a new
interrupt to be generated on the next transition of any
input point of that group. If the interrupt is serviced and
a Read PI command is issued, the PI register is not reset
and a new interrupt is not generated.
External
~n£ ~od~.
Figure 5-3 is a timing diagram for
Dr
external sync. This sequence is executed as follows:
1. The external sync mode is entered
by
performing the Arm
External Sync command. This causes the ready output
line to become active, indicating that the system is
ready for new input data.
2. A sUbsequent logical "zero" to logical "one" transition
on the external sync input
by
the user·s equipment
latches the group register, deactivates the ready line,
and posts an interrupt to the channel.
3. After the interrupt is serviced, a Read
Dr
command
reads the 01 register, resets the register, and
activates the ready line.
Diagno§!,!.£ l1ode. The diagnostic mode is entered by
performing either a Set Test Ones command or a Set Test
Zeros command. When the appropriate command is executed:
(1) the user's inputs are disabled, (2) either ones or zeros
are placed on the input receivers, and (3) the external sync
receiver is pulsed. Then when sUbsequent Read commands are
issued, the
Dr
group responds exactly as if the actual user
inputs had been set, including the PI and external sync
functions.
Integrated Digital I/O 5-7