Allen-Bradley ControlNet PLC-5 User Manual

1785-UM022B-EN-P - February 2002
Planning to Use Your ControlNet PLC-5 Processor 2-11
Clearing the PCSC New Data and PCSC Overflow Bits
If it is crucial to maintain the integrity of the PCSC overflow bit after
new data has arrived while clearing the PCSC new data and overflow
bits. Then do the following:
1. Disable process control sample complete by setting the PCSC
enable bit for the connection to zero.
When process control sample complete is disabled, the system
will not modify the new data and overflow bits while you clear
them.
2. Clear the PCSC new data and the PCSC overflow bits.
3. Re-enable process control sample complete by setting the
connection’s PCSC enable bit back to one.
Considerations When Using PCSC
When using scheduled ControlNet 1.5 communications to analog I/O
(such as map entries) and you are using the PID instruction in the
PLC-5/15, then you should do the following:
• the analog module must be set up to use RTS (Real Time Sample)
mode
• set your analog RPI (Repetitive Packet Interval) to be at least
twice the RTS time
• your ladder program needs to set the PCSC enable bit
• your ladder program needs to use the PCSC done bit to condition
the execution of the PID instruction
• the PID loop update must equal the RTS rate
• your ladder program must use the PCSC overflow bit to take
appropriate action on an overflow condition
Understanding Scheduled
Connection Types
Scheduled connections are made to I/O devices such as I/O adapters
and to peer-to-peer devices such as other controllers.
There are some common scheduled connection types made from the
ControlNet PLC-5 to other Allen-Bradley products that are detailed
in the following section. These scheduled connection types have
certain behaviors and limitations that you must understand before
configuring the connections. The ControlNet PLC-5 can also make
scheduled connections to products not manufactured by
Allen-Bradley. Refer to the literature that accompanies those products
for information on their scheduled connection behavior.
Scheduled connection types made from the ControlNet PLC-5 to I/O
adapters can be made either to some or all of the discrete I/O on the
adapter (called a rack connection), or to individual modules (called a
module connection).
AB Drives

Allen-Bradley ControlNet PLC-5 Specifications

General

Brand	Allen-Bradley
Model	ControlNet PLC-5
Category	Controller
Language	English