Rockwell Automation 1336T Function Block Prog. Manual, Series A/B - Manual (Page 43)

2–9 System Component Detail
1336 FORCE — 5.9 August 1995
Once you have properly downloaded and compiled your execution
list, you can access the I/O (input/output) nodes associated with each
function block. An I/O node is a parameter that provides information
to or from a function block.
The function block I/O nodes are different from the standard linear
parameters. While the linear parameters always reference the same
information, the I/O nodes are dynamic. The drive allocates memory
for the function block parameters (I/O nodes) depending on the
execution list. Thus, the drive only allocates as much memory as you
need to execute your application.
Because the I/O nodes are dynamic, you cannot use fixed numbers
(such as parameter 723) to refer to function block nodes. Instead,
function block parameters are referenced by block ID number and
node number. The block ID number and node number are also
application dependent.
As the execution list is compiled, the drive allocates the I/O nodes
associated with each event as a group. You can have a maximum of
799 I/O nodes per execution list.
The function block type defines the required number of I/O nodes
and the characteristics of each node for a particular function block.
I/O nodes are numbered from zero up to the proper number of nodes,
with the input nodes numbered first. A function block with six
nodes, numbered from zero to five, is shown below.
Node 0
Node 1
Node 2
Node 3
Node 4
Node 5
Output 1
Output 2
Input
Enable
On mS
Off mS
Delay
To reference a specific node of a particular function block, you need
the block ID number and the node number. Using the figure shown
above, if you want to access the I/O node for Output 1, the node
number would be 4.
The way you reference the block ID and node number depends on
whether you are using DriveTools or a PLC. DriveTools allows you
to use a decimal format to reference nodes, while PLC block transfer
uses a single word value.
Understanding Function
Block I/O Nodes