American Dynamics PMC-4U-CACI - Manual (Page 28)

Hardware and Software Design • Manufacturing Services
P a g e 28
Applications Guide
Interfacing
The pin-out tables are displayed with the pins in the same relative order as
the actual connectors. The pin definitions are defined with noise immunity
in mind. The pairs are chosen to match standard SCSI II/III cable pairing to
allow a low cost commercial cable to be used for the interface.
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. Connecting external
voltage to the PMC-4U when it is not powered can damage it, as well as
the rest of the host system. This problem may be avoided by turning all
power supplies on and off at the same time. Alternatively, the use of OPTO-
22 isolation panels is recommended.
Keep cables short. Flat cables, even with alternate ground lines, are not
suitable for long distances. PMC-4U does not contain special input
protection. The connector is pinned out for a standard SCSI II/III cable to
be used. The twisted pairs are defined to match up with the PMC-4Ul pin
definitions. 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.