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.
Hardware and Software Design • Manufacturing Services
