Specifications

Parallel I/O
ZT 8832 SPECIFICS
The three parallel ports are available at connector J1; see page B-11
for pin assignments. In addition to the 24 I/O signals, connector J1
also supports ground and fused +5 V for direct interface to industry
standard I/O module mounting racks, such as Ziatech’s ZT 2226 or
those manufactured by Opto 22. The 1 A fuse is available from
Littelfuse (part number 275-001).
The two most significant parallel port signals are connected to other
devices in addition to the J1 connector. The most significant parallel
port signal (I/O address 220h, bit 7) is connected to J1 and the
watchdog timer. It functions as a strobe signal used to prevent the
watchdog timer from timing out. This connection is jumper
selectable. The second most significant parallel port bit (I/O address
220h, bit 6) is connected to J1 and the Light Emitting Diode (LED)
located next to connector J3.
The use of the parallel port with the watchdog timer is discussed in
Chapter 13. The use of the parallel port to control the LED is
discussed at the end of this chapter.
12-2