Reference – Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) User Manual

Page 407

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Reference

Appendix B
Programming Reference

B–12

Address

Bit

Classification

Description

S16H

DH-485 Baud
Rate

Status

This byte value contains the baud rate of the processor on the
DH-485 link.
The controller baud rate options are:

9600

19200 (default)

To change the baud rate from the default value, you must use a
programming device.

S17 to S21

Reserved

NA

NA

S22

Maximum
Observed Scan

i e

Dynamic
Configuration

This word indicates the maximum observed interval between
consecutive program cycles.

bser e

ca

Time

fi ra i

This value indicates, in 10 ms increments, the time elapsed in
the longest program cycle of the controller. Refer to S:3L for
more information regarding the program cycle. The controller
compares each last scan value to the value contained in S:22.
If the controller determines that the last scan value is larger
than the value stored at S:22, the last scan value is written to
S:22.

Resolution of the maximum observed scan time value is

+

0 to

10 ms. For example, the value 9 indicates that 80–90 ms was

observed as the longest program cycle.

Interrogate this value if you need to determine or verify the
longest scan time of your program.

S23

Reserved

NA

NA

S24

Index Register

Status

This word indicates the element offset used in indexed
addressing.

When an STI, high-speed counter, or Fault Routine interrupts
normal execution of your program, the original value of this
register is restored when execution resumes.

S25 to S29

Reserved

NA

NA

S30

STI Setpoint

Dynamic
Configuration

You enter the timebase to be used in the selectable timed
interrupt (STI). The time can range from 10 to 2550 ms. (This is
in 10ms increments, so valid values are from 0–255.) Your STI
routine executes per the value you enter. Write a zero value to
disable the STI.

To provide protection from inadvertent alteration of your
selection, program an unconditional MOV instruction containing
the setpoint value of your STI to S:30, or program a CLR
instruction at S:30 to prevent STI operation.

If the STI is initiated while in the REM Run mode by loading the
status registers, the interrupt starts timing from the end of the
program scan in which the status registers were loaded.

S31 to S32

Reserved

NA

NA

Address is not shown in HHP data monitor.

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