Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 601)

Section 10B
9/Series Adapter Modules for
1771 and 1746 I/O Devices
10B-12
Important: Each analog channel on an analog module must be counted.
Even if the channel is not used or jumpered out it must be counted as a
channel on the ring.
The largest of A, B, or C determines the total number of ASRN “chips” for
the 1746 and 1771 I/O configuration.
Example: A 1746 4-slot chassis, one 16-point input card, one 8-point
output card, and an analog module with two input and two output channels
(1746-NIO4V).
A = 4 slot chassis = (3 ASRN)
(16) + (16)(2)
11
= 4.36 (5 ASRN) B =
(8) + (16)(2)
6
= 6.66 (7 ASRN) C =
The 1746 chassis in this example will use 7 ASRN “chips” (the largest
value of A, B, or C).
The number of ASRN “chips” used by the chassis must be added to the
total number of ASRN “chips” used by all the I/O devices on the current
I/O ring. Refer to page 10A-2 for information on the number of ASRN
chips used by other 9/Series I/O ring devices.
Important: The total number of ASRN chips allowed on the fiber optic
ring is shown in Table 10A.B for each processor type. 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.
END OF SECTION