Rockwell Automation 1336T Function Block Prog. Manual, Series A/B - Manual (Page 46)

2–12 System Component Detail
1336 FORCE — 5.9 August 1995
Node Data Types
The value of a function block I/O node will be one of the following
types:
❒
A signed decimal integer with a value range of
±
32767.
❒
An unsigned decimal integer with a value range of 0 – 65535.
❒ A logical value where 0 = False and any non-zero value = True.
Some nodes have additional range restrictions. For example, a node
may be a signed integer with a range of
±
16383 instead of
±
32767.
In addition, nodes may be linkable or non–linkable. A linkable node
is a node which is able to receive information from another source,
while a non–linkable node cannot receive information from another
source. Input nodes may be either linkable or non-linkable. Output
nodes are not linkable. However, you can use output nodes to
provide data for inputs to other function blocks or to drive linear
parameters.
When you connect function blocks, you need to be careful. Linkable
inputs can get data from any function block node or linear parameter,
regardless of its data type. As an example, you could link a logical
input to a signed decimal output.
The characteristics of the destination node determine how the input
value is interpreted. In the case where a signed decimal output is
linked to a logical input, the value would be interpreted as a true
value unless the source value (such as a velocity or position
feedback) was equal to zero.