Dynamic Engineering PMC-PARALLEL-TTL User Manual page 30

Applications Guide
Interfacing
The pin-out tables are displayed with the pins in the same relative order as the actual
connectors. Some general interfacing guidelines are presented below. Do not hesitate
to contact the factory if you need more assistance.
Watch the system grounds. All electrically connected equipment should have a fail-safe
common ground that is large enough to handle all current loads without affecting noise
immunity. Power supplies and power-consuming loads should all have their own ground
wires back to a common point.
Power all system power supplies from one switch. Open Drain interface devices provide
some immunity from and allow operation when part of the circuit is powered on and part
is not. It is better to avoid the issue of going past the safe operating areas by powering
the equipment together and by having a good ground reference.
Keep cables short. Flat cables, even with alternate ground lines, are not suitable for
long distances. The PMC-Parallel-TTL has transorbs for input protection. The connector
is pinned out for a standard SCSI II/III cable to be used. It is suggested that this
standard cable be used for most of the cable run.
Terminal Block. We offer a high quality 68 screw terminal block that directly connects to
the SCSI II/III cable. The terminal block can mount on standard DIN rails. HDEterm68
[ http://www.dyneng.com/HDEterm68.html ]
We provide the components. You provide the system. Safety and reliability can be
achieved only by careful planning and practice. Inputs can be damaged by static
discharge, or by applying voltage outside of the particular device's rated voltages.
Embedded Solutions Page 30