EMERSON PACSystems VersaMax MICRO PLC & NANO PLC. USER MANUAL (2019) - page 23

User Manual

Chapter 16

GFK-1645M

Dec 2019

Configuration

322

Channel Function: Pulse Train with Ramp

(Micro-20, Micro-40, and Micro-64 PLCs). If the Counter Type is configured as either 4 Type
A or 1 Type A / 1 Type B (this choice is not available for 4 Type A_32 or 1 Type A / 1 Type
B_32), selecting Pulse Train with Ramp sets up the channel as a Pulse Train output with the
ability to accelerate and decelerate. See Chapter 17: for a description of this feature.

The Counter Status parameter enables or disables the pulse output.

PTR Acceleration sets up the Pulse Train acceleration rate, from stop to full speed. For
channels 1, 2, and 3, the range is 10 through 1,000,000. For channel 4, the range is 90 to
1,000,000.

PTR Deceleration sets up the Pulse Train deceleration rate, from full speed to stop. For
channels 1, 2, and 3, the range is 10 through 1,000,000. For channel 4, the range is 90 to
1,000,000.

Channel Function: Motion Support

(Micro-20, -40, and -64 PLCs only. This feature requires Machine Edition version 5.5 SP2,
Sim2 or later). Selecting Motion Support as the Channel Function sets up the channel as a
Pulse Train output with the ability to accelerate and decelerate. See Chapter 18: for a
description of this feature.

The Counter Status parameter enables or disables the pulse output.

The User Units and Counts parameters set up a scaling factor for the Acceleration and
Deceleration parameters of a motion profile. The possible ratio of User Units to Counts is
1:16 through 8:1.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

323

Chapter 17:

PLC Operation

This chapter describes the operating modes of the VersaMax Nano and Micro PLCs and
shows the relationship between the application program execution and other tasks
performed by the PLC CPU.

17.1

Operating Modes

The application program in a PLC executes repeatedly. In addition to executing the
application program, the PLC regularly obtains data from input devices, sends data to
output devices, performs internal housekeeping, and performs communications tasks. This
sequence of operations is called the sweep.

•

The basic operating mode of the PLC is called Standard Sweep mode. In this mode,
the CPU performs all parts of its sweep normally. Each sweep executes as quickly as
possible with a different amount of time consumed each sweep.

•

The PLC may instead operate in Constant Sweep Time mode. In this mode, the CPU
performs the same series of actions but each sweep takes the same amount of time.

•

The PLC may also be in either of two Stop modes:

—

Stop with I/O Disabled mode

—

Stop with I/O Enabled mode

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

324

17.2

Parts of the CPU Sweep

Figure 182

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

325

Parts of the CPU Sweep

Start of Sweep
Housekeeping

Housekeeping includes the tasks necessary to prepare for the start of the
sweep. Before starting the actual sweep, the CPU:

•

calculates the sweep time

•

Schedules the start of the next sweep

•

Determines the mode of the next sweep

•

Updates the fault reference tables

•

Resets the Watchdog timer

If the PLC is in Constant Sweep Time mode, the sweep is delayed until the
required sweep time elapses.  If the required time has already elapsed, the
OV_SWP  %SA0002  contact  is  set,  and  the  sweep  continues  without  delay.
Next, the CPU updates timer values (hundredths, tenths, and seconds).

Input Scan

When  the  sweep  starts,  the  CPU  first  scans  inputs  in  ascending  reference
address  order.  The  CPU  stores  this  new  input  data  in  the  appropriate
memories.
If the CPU has been configured to not scan I/O in Stop mode, the input scan is
skipped when the CPU is in Stop mode.

Application
Program Logic
Scan

Next, the CPU solves the application program logic. It always starts with the
first instruction in the program. It ends when the END instruction is executed.
Solving the logic creates a new set of output data.

Output Scan

Immediately after the logic solution, the CPU scans all outputs in ascending
reference address order. The output scan is completed when all output data
has written.
If the CPU has been configured to not scan I/O in Stop mode, the output scan
is also skipped when the CPU is in Stop mode.

Programmer
Communications
Window

If  there  is  a  programming  device  attached,  the  CPU  next  executes  the
programmer communications window.
In the default limited window mode, each sweep the CPU honors one service
request.    The  time  limit  for  programmer  communications  is  6  ms.  If  the
programmer makes a request that requires more than 6 ms to process, the
processing is spread out over multiple sweeps.
In  Run  to  Completion  mode,  the  length  of  the  system  communications
window is limited to 50 ms. If a module makes a request that requires more
than 50 ms to process, the request is spread out over multiple sweeps

System
Communications
Window

Next, the CPU processes communications requests. In default (“Run to
Completion”) mode, the length of the system communications window is

limited to 200 ms. If a request requires more  than 200 ms  to process, the
request is spread out over multiple sweeps.
In  Limited  mode,  if  a  request  requires  more  than  6  ms  to  process,  the
processing  is  spread  out  over  multiple  sweeps.  The  result  is  that
communications using the system window have less impact on sweep time,
but response is slower.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

326

Parts of the CPU Sweep

Logic Program
Checksum
Calculation

A checksum calculation is performed on the application program at the end
of every  sweep.  You  can specify  the  number  of words from 8 to 32 to be
checksummed.
If  the  calculated  checksum  does  not  match  the  reference  checksum,  the
program checksum failure exception flag is raised.  This causes a fault entry
to be inserted into the PLC fault table and the PLC mode to be changed to
Stop.    If  the  checksum  calculation  fails,  the  programmer  communications
window is not affected.

17.3

Standard CPU Sweep Operation

Standard Sweep operation is the normal operating mode of the PLC CPU. In Standard
Sweep operation, the CPU repeatedly executes the application program, updates I/O, and
performs communications and other tasks shown in the diagram:

The CPU performs its start-of-sweep housekeeping tasks.

It reads inputs.

It executes the application program.

It updates outputs

If a programming device is present, the CPU communicates with it.

It communicates with other devices.

It performs diagnostics

Except for communicating with a programmer, all these steps execute every sweep.
Programmer communications occur only when needed.

In this mode, the CPU performs all parts of its sweep normally. Each sweep executes as
quickly as possible with a different amount of time consumed each sweep.

17.3.1

The Sweep Windows

The programmer communications window and the system communications window have
two operating modes:

Limited Mode

The execution time of the window is 6ms. The window
terminates when it has no more tasks to complete or when
6ms has elapsed.

Run to Completion Mode

Regardless of the time assigned to a particular window, the
window runs until all tasks within that window are
completed (up to 200ms for the System Communications
Window and up to 50ms for the Programmer
Communications Window).

SVCREQ 2 can be used in the application program to obtain the current times for each
window.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

327

17.3.2

The Watchdog Timer

When the CPU is in Standard Sweep mode, the watchdog timer catches failure conditions
that could cause an unusually long sweep. The length of the watchdog timer is 200ms. It
restarts from zero at the beginning of each sweep.

If the sweep takes longer than 200mS, the OK LED on the CPU module goes off. The CPU
resets, executes its power-up logic, generates a watchdog failure fault, and goes to Stop
mode. Communications are temporarily interrupted.

17.4

Constant Sweep Time Operation

If the application requires that each CPU sweep take the same amount of time, the CPU can
be configured to operate in Constant Sweep Time mode. This operating mode assures that
the inputs and outputs in the system are updated at constant intervals. This mode can also
be used to implement a longer sweep time.

17.4.1

Changing the Configured Default for Constant Sweep
Mode

If the PLC is in STOP mode, its Configured Constant Sweep mode can be edited. After this is
done, the configuration must be stored to the CPU for the change to take effect. Once
stored, Constant Sweep Time mode becomes the default sweep mode.

17.4.2

The Constant Sweep Timer

During op

eration in Constant Sweep Time mode, the CPU’s constant sweep timer controls

the length of the sweep. The timer length can be 5 to 200 ms. The time should be at least

10 ms longer than the CPU’s sweep time when it is in Standard Sweep mode, to prevent

extraneous over-sweep faults.

If the constant sweep timer expires before the sweep completes, the CPU still completes the
entire sweep, including the windows. However, it automatically provides notice than a too-
long sweep has occurred. On the next sweep after the over-sweep, the CPU places an over-
sweep alarm in the PLC fault table.  Then, at the beginning of the following sweep, the CPU
sets  the  OV_SWP  fault  contact  (%SA0002).    The  CPU  automatically  resets  the  OV_SWP
contact when the sweep time no longer exceeds the Constant Sweep Timer. The CPU also
resets the OV_SWP contact if it is not in Constant Sweep Time mode.

As with other fault contacts, the application program can monitor this contact to keep
informed about the occurrence of over-sweep conditions.

17.4.3

Enabling/Disabling

Constant

Sweep

Time,

Reading or Setting the Length of the Timer

SVCREQ 1 can be included in the application program to enable or disable Constant Sweep
Time mode, change the length of the Constant Sweep Time, read whether Constant Sweep
Time is currently enabled, or read the Constant Sweep Time length.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

328

17.5

CPU Stop Modes

The Nano or Micro PLC may be in either of two Stop modes:

•

Stop with I/O Disabled mode

•

Stop with I/O Enabled mode

When the PLC is in Stop mode, the CPU does not execute the application program logic. You
can configure whether or not the I/O will scanned during Stop mode. Communications with
the programmer and intelligent option modules continue in Stop mode. In addition, faulted
board polling and board reconfiguration execution continue in Stop mode.

SVCREQ 13 can be used in the application program to stop the PLC at the end of the next
sweep. All I/O will go to the OFF state and a diagnostic message will be placed in the PLC
Fault Table.

17.6

Controlling the Execution of a Program

The VersaMax CPU Instruction Set contains several powerful Control functions that can be
included in an application program to limit or change the way the CPU executes the
program and scans I/O.

17.6.1

Calling a Subroutine Block

The CALL function can be used to cause program execution to go to a specific subroutine.
Conditional logic placed before the Call function controls the circumstances under which
the CPU performs the subroutine logic. After the subroutine is finished, program execution
resumes at the point in the logic directly after the CALL instruction.

17.6.2

Creating a Temporary End of Logic

The END function can be used to provide a temporary end of logic. It can be placed
anywhere in a program. No logic beyond the END function is executed, and program
execution goes directly back to the beginning. This ability makes the END function useful
for debugging a program.

The END function should not be placed in logic associated with or called by a Sequential
Function Chart control structure. If this occurs, the PLC will be placed in STOP/FAULT mode
at the end of the current sweep and an SFC_END fault will be logged.

17.6.3

Executing Rungs of Logic without Logical Power Flow

The nested Master Control Relay can be used to execute a portion of the program logic with
no logical power flow. Logic is executed in a forward direction and coils in that part of the
program are executed with negative power flow. Master Control Relay functions can be
nested to 8 levels deep.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

329

17.6.4

Jumping to Another Part of the Program

The Jump function can be used to cause program execution to move either forward or
backward in the logic. When a nested Jump function is active, the coils in the part of the
program that is skipped are left in their previous states (not executed with negative power
flow, as they are with a Master Control Relay). Jump functions can also be nested.

Jumps cannot span blocks, SFC actions, SCF transitions, or SFC pre- or post-processing logic.

17.7

Privilege Levels and Passwords

Passwords are an optional configurable feature of the Micro PLC (passwords are not
available on Nano PLCs). Passwords provide different levels of access privilege to the PLC
when the programmer is in Online or Monitor mode. Passwords are not used if the
programmer is in Offline mode. Passwords can restrict:

•

Changing I/O and PLC configuration data

•

Changing programs

•

Reading PLC data

•

Reading programs

There is one password for each privilege level in the PLC. Each password may be unique or
the same password can be used for more than one level. Passwords are one to seven ASCII
characters in length.

By default, there is no password protection. Passwords are set up, changed, or removed
using the programming software. After passwords have been set up, access to the PLC is
restricted unless the proper password is entered. Entering a correct password allows access
to the requested level and to all lower levels. For example, the password for level 3 allows
access to levels 1, 2, and 3. If PLC communications are suspended, protection automatically
returns to the highest unprotected level. For example: If a password is set at levels 2 & 3, but
none at level 4, if the software disconnects and reconnects, the access level is 4. Privilege
level 1 is always available because no password can be set for this level.

Level

Access Description

4 Least
Protected

•

Write to all configuration or logic. Configuration may only be written in Stop
mode; logic may be written in Stop or Run mode (if run-mode store is
supported).

•

Set or delete passwords for any level.

•

Plus all access from levels 3,2 and 1

Note:

This is the default if no passwords are defined.

•

Write to all configuration and logic when the CPU is in Stop mode, including
word-for-word changes (when supported), the addition/deletion of program
logic, and the overriding of discrete I/O.

•

Read/Write/Verify user flash.

•

Store reference/override tables.

•

Change sweep mode.

•

Plus all access from levels 2 and 1

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

330

Level

Access Description

•

Write to any data memory, but this does not include storing tables.

•

This includes the toggle/force of reference values but does not include
overriding discrete I/O.

•

The PLC can be started or stopped.

•

PLC and I/O fault tables can be cleared.

•

Plus all access from level 1

1 Most
Protected

Read any PLC data except for passwords. This includes reading fault tables, current
status, performing datagrams, verifying logic/config, and loading program and
configuration from the PLC. No PLC memory may be changed.

17.7.1

Protection Level Request from Programmer

Upon connection to the CPU, the programming software automatically requests the CPU to
move to the highest unprotected level. That gives the programmer access to the highest
unprotected level without having to specifically request a particular level.

A privilege change may be to a lower level or to a higher level. The privilege level is changed
from the programmer by entering the new level and the correct password for that level. If
the wrong password is entered, the change is denied and a fault is logged in the PLC fault
table. A request to change to a privilege level that is not password-protected is made by
supplying the new level and an empty password.

Notes on Using Passwords

To re-enable passwords after passwords have been disabled, the PLC must be power-cycled
with the battery removed for long enough to completely discharge the super-capacitor and
erase the PLC memory.

If the passwords prevent changing the run/stop mode, firmware upgrades cannot be
performed if the PLC is in run mode.

The Run/Stop switch (if configured) will place the PLC in run or stop mode regardless of the
passwords.

17.7.2

The OEM Protection Feature

The OEM protection feature is similar to the passwords and privilege levels and provides an
even  higher  level  of  security.  The  feature  is  enabled  or  disabled  using  a  1  to  7  character
password called the OEM key. When OEM protection is enabled, no write-access to the PLC
program  and  configuration  is  permitted.  Reading  the  configuration  from  the  PLC  is
permitted.  In this mode, no user flash operations are allowed.

When the OEM key password has been created, the OEM key can be locked in two ways: by
choosing the locked setting from the programming software or by power-cycling the PLC.
(The OEM key locked status does not change when PLC communications are suspended.)

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

331

17.7.3

Clearing All Memory

It is possible to Clear All memory from the programmer with the CPU at any privilege level,
even with the OEM key locked. Operators can clear CPU memory and store a new application
program to the CPU without knowing passwords.

If passwords and/or the OEM key have been set and written to flash, a read from flash
updates the protection level. In this case, it is not necessary to re-enter the password to gain
access to a particular level. A Clear All does not clear user flash.

17.8

Run/Stop Mode Switch Operation

The CPU Run/Stop mode switch on a VersaMax Micro PLC can be used as a Run/Stop switch,
as a memory protect switch, and for clearing faults when a fatal fault exists.

A 10-Point VersaMax Nano PLC can provide the same functionality by adding a Single Pole,
Single Throw (SPST) switch. An external switch on a Nano PLC is read as a normal 24Vdc
input. The specifications for the RUN input are the same as the other DC inputs on the Nano
PLC.

17.8.1

Run/Stop Mode Operation

If Run/Stop operation is enabled, the Run/Stop switch is use to control the operating mode
of the PLC. The PLC monitors the state of the Run/Stop switch and stores the current state
in status bit %S0022. The application program can check the state of this bit if necessary,
and activate logic based on its setting (in Run mode, the bit is =1, and in Stop mode, it is =0).

If Run/Stop mode switch operation is enabled, the switch can be used to place the Micro PLC
CPU in Run mode if a fatal fault condition exists in the CPU. Note that the switch overrides
any restrictions on mode selection that have been set up using password protection.

•

If the CPU has non-fatal faults and is not in Stop/Fault mode, placing the switch in
Run position causes the CPU to go to Run mode. Faults are NOT cleared.

•

If  the  CPU  has  fatal  faults  and  is  in  Stop/Fault  mode  and  Run/Stop  Enabled  is
configured,  placing  the  switch  in  Run  position  causes  the  Run  LED  to  blink  for  5
seconds. While the Run LED is blinking, the CPU switch can be used to clear the fault
table and put the CPU in Run mode. After the switch has been in Run position for at
least ½ second, move it to Stop position for at least ½ second. Then move it back to
Run position. The faults are cleared and the CPU goes to Run mode.  The LED stops
blinking and stays on. This can be repeated if necessary.

•

If the switch is not toggled as described, after 5 seconds the Run LED goes off and
the CPU remains in Stop/Fault mode. Faults stay in the fault table.

•

If Run/Stop operation is NOT enabled by configuration and a fatal fault occurs, it is
not possible to restore operation using the switch as described above. The CPU
remains in Stop/Fault mode and faults stay in the fault table.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

332

17.8.2

Configurable Memory Protection

Operation of the Micro PLC Run/Stop switch (or Nano Run/Stop input) can be configured to
prevent writing to program memory and configuration, and to prevent forcing or overriding
discrete data.

17.8.3

Configuration Parameters and Switch Position for
Run/Stop Modes

Switch
Run/Stop
Enabled
Configuration

I/O Scan Stop
Configuration

Switch
Position

Allowed
Mode

PLC Operation

Disabled

has no effect

All

PLC Programmer modes
operate the same

Enabled

has no effect

Run/On

All

PLC Programmer modes
operate the same

Enabled

Stop/Off

Stop/ No I/O

PLC not allowed to go to
Run mode.

Enabled

Yes

Stop/Off

Stop/No I/O,
Stop I/O

PLC not allowed to go to
Run mode.

Enabled

has no effect

Toggle Switch
from Stop to
Run

n/a

PLC goes to Run mode

Enabled

Toggle switch
from Run to
Stop

n/a

PLC goes to STOP

–

NO IO

Enabled

Yes

Toggle switch
from Run to
Stop

n/a

PLC goes to STOP

–

17.8.4

Configuration Parameters and Switch Position for
Memory Protection

Memory Protect Enabled
Configuration

Switch Position

PLC Operation

Off

n/a

Normal PLC operation

Protect/On

No storing/clearing/loading of PLC allowed

Protect/Off

Normal PLC operation

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

333

17.8.5

Configuration Parameters and Switch Position for
Simultaneous Run/Stop Operation and Memory
Protection

Memory Protect
Configuration

Run/Stop
Configuration

Switch Position

PLC Operation

Enabled

Disabled

Toggled from OFF to ON Memory Protected

Enabled

Toggled from OFF to ON Memory Protected

PLC is in Run Mode

Enabled

Toggled from ON to OFF Memory Protected

PLC is in Stop Mode
PLC cannot be put in Run
Mode with Programmer

17.8.6

Configuration Parameters and Switch Position for Fault
Operations

Run/Stop
Enabled
Configuration

Switch Position

Faults Present
in the PLC

PLC Operation

Disabled

n/a

Normal PLC operation

Enabled

Toggle Switch from Stop to Run Non-fatal

Places PLC in Run mode
Faults are NOT cleared

Enabled

Toggle Switch from Stop to Run Fatal

Run LED blinks for 5 sec

Enabled

While the Run LED is blinking and
ON for at least ½ second, toggled
from Run to Stop, and then, after
another ½ second, toggled from
Stop to Run

Fatal

PLC goes to Run mode
and all faults are cleared

17.9

Power-Up and Power-Down Sequence

17.9.1

Power-Up Sequence

The power-up sequence for the Nano/Micro PLC consists of the following events:

The CPU runs self-diagnostics. This includes checking a portion of RAM to determine
whether or not the RAM is functional. (For DC Micro PLCs, power-up diagnostics can
be disabled by configuration. It is recommended that you not use this feature unless
your application requires unusually rapid power-

up. For details, see “Installation

Instructions”.)

The hardware configuration is compared with the software configuration. Any
mismatches detected constitute faults and are alarmed.

If there is no software configuration, the CPU uses the default configuration.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

334

The mode of the first sweep is determined based on CPU configuration. The PLC can
either copy the program from flash memory into RAM (see below), or power up in

Stop or Run mode. See “Flash Memory”.

Nano PLC or 14-
Point Micro PLC

23-Point or 28-Point Micro PLC

No Backup Battery

Backup Battery

Default Power-
up Mode

Stop Mode

Last Mode

Configurable
Power-up
Modes

Run Mode or Stop
Mode

Run, Stop, or Last Mode

17.9.2

Flash Memory

A VersaMax Nano or Micro PLC provides non-volatile flash memory to store the application
program and system firmware.

Only one application program at a time can be present in non-volatile flash memory.
Separate copies of the user data (program, configuration, and retentive data) are
maintained in FLASH memory.

During configuration of a Nano or Micro PLC, you can choose whether, in the future, the PLC
will read its user data from flash or from RAM.

In addition, Micro PLCs that use the optional backup battery can read their user data from
RAM if the unit has been powered down for an extended period of time. If there is no battery
backup, RAM may be invalid on power-up. In that case, the default program is installed, or
the user data must be read from flash.

User Data

Configuration Program

Retentive Data

Default Settings

Read From RAM

Read From FLASH

–

Recommended Settings

Read From RAM

–

Read From FLASH

X
(If battery is not used)

If the application uses SVCREQ 53 to write additional data to flash memory (supported in
firmware rev 3.0), retentive data will be updated. If the retentive data is read from flash on
power-up, these updated values will be used instead of the original data values.

17.9.3

Default Conditions for Micro PLC Output Points

At power-up, output points default to off. They stay off until the first output scan.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

335

17.9.4

Power-Down Conditions

System power-down occurs automatically if the power supply detects that incoming AC
power has dropped. The minimum hold time is one half cycle.

Note:

During a gradual power down, when the input power supply voltage drops below the minimum
operating voltage, the PLC will transition to a state where all outputs are disabled. In this state,
the Run LED and the OK LED are also turned off. The PLC remains in this state until power is lost
completely (the PLC shuts off), or until power is restored (above the minimum operating voltage).
In the latter case, the PLC will reset itself and start the normal power-up sequence.

17.9.5

Power Cycle

The table below lists the effects that a power cycle can have on Micro PLC operation under
specific conditions.

Condition

Effects

PLC loses power while storing a program
to RAM from either the programming
software or flash memory.

On the ensuing power-up the program will be deleted
from RAM. You will need to store the program again
from the programmer.

PLC loses power while storing a
configuration to RAM from either the
programming software or flash memory.

On the ensuing power-up, the configuration will be
deleted from RAM. You will need to store the
configuration again from the programmer.

PLC loses power while storing the
reference tables to RAM from either the
programming software or flash memory.

On the ensuing power-up, the reference table data
will be deleted from RAM. You will need to store the
data again from the programmer.

PLC loses power while storing a program,
configuration, or reference table data to
flash memory.

The  flash  memory  area  used  to  store  the  program,
configuration,  or  reference  table  data  will  be
considered  invalid.  You  will  need  to  store  the
program, configuration, or reference tables to flash
memory again.

If system includes expansion unit(s):

Micro PLC base unit loses power before the
expansion unit(s)

Expansion units will be reset (all outputs will be set to
zero)

Expansion unit(s) lose power before the
Micro PLC base unit while Micro PLC is
scanning I/O

A Loss of Expansion Module fault may be logged.

Micro PLC base unit powers up before the
expansion unit(s)

If expansion units do not power up at the same time
as the Micro PLC, a Loss of Expansion Module fault
may be logged.

Expansion unit(s) power up before the
Micro PLC base unit

Expansion unit outputs remain off until the Micro
base unit completes power-up and begins scanning
I/O.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

336

17.10

Input Filters

17.10.1

Discrete Input Filtering

Nano and Micro PLCs with DC inputs can provide discrete input filtering, to compensate for
switch bounce and other application conditions. This input filtering also applies to discrete
expansion units connected to the PLC.

Filter Control Reference

Discrete input filter time can be changed on the fly by simply adjusting the value in reserved
reference %AQ11. The filter time can be 0.5mS to 20mS in 0.5mS increments. The value in
%AQ11 represents the number of 0.5mS increments in the total filter time.

For 20/40/64-point Micro PLCs, input filtering is configurable in 1ms increments only. Use
the values shown below (1ms = 2, 2ms = 4, 3ms = 6 and so on).

Note that input filtering is not provided for 64-point expansion units.

Filter
Time in
mS

Value to
Put in
%AQ11

Filter

Time in
mS

Value to
Put in
%AQ11

Filter

Time in
mS

Value to
Put in
%AQ11

Filter

Time in
mS

Value to
Put in
%AQ11

0.5mS

5.5mS

10.5mS

15.5mS

1.0mS

6.0mS

11.0mS

16.0mS

1.5mS

6.5mS

11.5mS

16.5mS

2.0mS

7.0mS

12.0mS

17.0mS

2.5mS

7.5mS

12.5mS

17.5mS

3.0mS

8.0mS

13.0mS

18.0mS

3.5mS

8.5mS

13.5mS

18.5mS

4.0mS

9.0mS

14.0mS

19.0mS

4.5mS

9.5mS

14.5mS

19.5mS

5.0mS

10.0mS

15.0mS

20.0mS

The input filter recognizes signals that have a duration within ±0.5mS (±1.0mS for 20-/40-
/64-point Micro PLCs) of the filter time. For example, if the filtering time is 5mS, any input
that lasts more than 4.5mS (5.0mS for 20-/40-/64-point Micro PLCs) is recognized. What
will be read on an input is not only based on the input filter setting. It is also based on the
scan time. An input will always be seen if it is longer than both the scan time and the filter
time.

Because %AQ11 is used to control the discrete input filtering time, it should not be used for
any other purpose.

User Manual

Chapter 17

GFK-1645M

Dec 2019

PLC Operation

337

17.11

Hardware R/C Filters

In addition to Discrete Input Filters, all the VersaMax Nano/Micro modules have simple
Hardware R/C Filters for the inputs. The following table provides the filter constants of the
simple hardware R/C filter present on each module.

Module

I1 to I4

I5 to I6

I7 to I8

I9 to I12

I13

I14 to I16

I17 to I24

I25 to I40

IC200NDR001

200nS

IC200NAL211

200nS

IC200NDD101

200nS

IC200NDR010

200nS

IC200NAL110

200nS

IC200NDD010

200nS

IC200UAR014

20 mS

IC200UAA003

20 mS

IC200UDR001

200nS

IC200UDR002

200nS

IC200UDD104

200nS

IC200UDR003

200nS

IC200UDD112

200nS

IC200UDR120

100nS

IC200UDR020

100nS

IC200UDD220

100nS

IC200UDD020

100nS

IC200UAL006

200nS

IC200UAL005

200nS

IC200UAL004

200nS

IC200UAR028

20mS

IC200UAA007

20mS

IC200UDR005

200nS

IC200UDR010

200nS

IC200UDD110

200nS

IC200UDD120

200nS

IC200UDR006

200nS

IC200UDD212

200nS

IC200UDR228

200nS

IC200UDR140

100nS

IC200UDR040

100nS

IC200UDD240

100nS

IC200UDD040

100nS

IC200UDR440

100nS

Content .. 21 22 23 24 ..