Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 525)

I/O Interface
Section 10A
10A-2
ATTENTION: When the control faults or loses power, all I/O
devices remain in their last state. I/O devices do not
automatically reset to an off state. It is the system installers
responsibility to make sure that all I/O is in a safe state when a
control shut down occurs. 1771 I/O devices have a dip switch
on the backplane that determines the shutdown state for I/O in
that 1771 I/O chassis when used with a PLC-5 processor. This
dip switch does not have any effect when 1771 I/O devices are
used with a 9/Series control.
Each I/O device requires a specific amount of update time regardless of the
number of inputs and outputs actually connected to the device. This is
because devices on the I/O ring use Asynchronous Serial Ring Network
circuits (referred to as ASRN “chips”) for input and output transmission.
These chips are constantly scanned through the fiber optic ring by the
control. Table 10A.A lists the number of ASRN “chips” per device and the
number of I/O points per device.
Important: The total number of ASRN chips allowed on the fiber optic
ring is dependent on your processor as shown in Table 10A.B. Exceeding
this number creates an E-STOP condition. Since your system scan time is
configurable in AMP it is possible to set the system scan time so low that
the control will not complete the I/O scan of all the ASRNs in your ring.
When this occurs old data may be made available to PAL. On systems
with large I/O rings and low system scan times, the PAL flag $RNGS
should be used to test if the system has completed the I/O scan and made
all the necessary ring I/O updates.
Table 10A.A
I/O Ring Modules Connectors
I/O Ring Modules Number of ASRN Chips Number of I/O Points
Operator Panel (standard non-portable) 1 1 8-bit Input
Portable Operator Panel Interface Assembly 1 1 8-bit Input
HPG 1 1 6-bit Input
Pushbutton MTB Panel I/O Module 4 44 Digital Inputs; 18 Digital Outputs
Digital I/O 2 20 Digital Inputs; 12 Digital Outputs
High--density I/O Module 6 66 Digital Inputs; 33 Digital Outputs
Analog I/O 2 1 12-bit Analog Input; 1 12-bit Analog Output
1394 Digital Drive 2 21 Digital Inputs (see appendix H for addressing)
1746 24V dc Digital I/O Assembly (S24) 3 32 inputs, 16 outputs
1746 110V ac Digital I/O Assembly (S115) 3 32 Inputs, 16 Outputs
1746 Analog I/O Assembly (SANL) 6 2 analog input channels, 2 analog output channels
Other 1746 or 1771 I/O Chassis see page 10B-10 Depends upon modules used