snap ethernet-based i/o units protocols and programming guide

Analog and Digital Systems (N Brains)
CHAPTER 2: OVERVIEW OF PROGRAMMING
The following diagram applies to systems with SNAP-UPN-ADS brains. The brain and I/O
modules are mounted on a SNAP N-series mounting rack, which can hold either 8 or 12 Opto 22
SNAP I/O modules. The first eight module positions can hold any combination of analog, digital,
or serial modules. Beyond eight positions, N-series racks hold analog or serial modules only. (For
more information, see the data sheet for your rack.)
Each SNAP digital module contains four input or four output channels (points). SNAP analog
modules supported by these brains contain either two or four points.
CAUTION: Do NOT connect these brains to any other rack. They are designed for use with
N-series racks only. Using any other rack will severely damage the brain.
Each point on the rack is numbered; when you configure the point or read or write to it, you
reference it by its number. The following diagram shows the largest rack as an example. Note
that four numbers are shown for each analog module. If you are using analog modules that
contain only two points, ignore the upper two point numbers.
Module position 0
NOTE: Analog modules can be
placed in any position; digital
modules can be placed in
positions 0–7 only.
SNAP Ethernet-Based I/O Units Protocols and Programming Guide 15