A-3.4 I/O Scan And I/O Fault Sweep Impact - GE PACSystems RX7i Reference Manual

Appendix A. Performance Data
A-3.4 I/O Scan and I/O Fault Sweep Impact
The I/O scan sweep impact has two parts, Local I/O and Genius I/O. The equation for computing I/O scan
sweep impact is:
I/O Scan Sweep Impact
Sweep Impact of Local I/O Modules
The I/O scan of I/O modules is impacted as much by location and reference address of a module as it is
by the number of modules. The I/O scan has several basic parts.
I/O Scan
Rack Setup Time
Per Module Setup Time Each Local I/O module has a fixed setup scan time.
Byte Transfer Time
In addition, analog input expander modules (the same as Genius blocks) have the ability to be grouped
into a single transfer as long as consecutive reference addresses are used for modules that have
consecutive slot addresses. Each sequence of consecutively addressed modules is called a scan segment.
There is a time penalty for each additional scan segment.
RX7i I/O Module Types
Type
Discrete Input Type I
(16-point, 14-point)
Discrete Input Type II
(32-point)
Discrete Output Type I
(16-point, 12-point)
Discrete Output Type II
(32-point)
Analog Input Type I
(8-Channel)
Analog Input Type II
(16-Channel with 8-channel AI
module)
Analog Output
(4-channel)
280
= Local Scan Impact
Description
Each expansion rack is selected separately because of the addressing of
expansion racks on the VME bus. This results in a fixed overhead per
expansion rack, regardless of the number of modules in that rack.
The actual transfer of bytes is much faster for modules located in the main
rack than for those in expansion racks. The byte transfer time differences will
be accounted for by using different times for I/O modules in the main rack
versus expansion racks.
Part Numbers
IC697MDL240, IC697MDL241, IC697MDL251, IC697MDL640,
IC697MDL671
IC697MDL250, IC697MDL252, IC697MDL253, IC697MDL254,
IC697MDL651, IC697MDL652, IC697MDL653, IC697MDL650,
IC697MDL654
IC697MDL340, IC697MDL341, IC697MDL740, IC697MDL940
IC697MDL350, IC697MDL750, IC697MDL752, IC697MDL753
IC697ALG230
IC697ALG440, IC697ALG441
IC697ALG320
PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual
+ Genius I/O Scan
Impact
GFK-2222AD