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Each instance of a motion function block in the program requires a separate memory area
for its internal status and control data. This must be set up by assigning two contiguous
words of %R memory during programming. The reference address location is initially
indicated by ???? in the function block.

During operation, the data in these assigned status and control references should not be
overwritten by user logic. Overlapping reference addresses may cause erratic operation of
the motion function block.

The first word of this data area is used for 16 status and control bits. As the table below
shows, the Find Home, Go Home, Blending, and Stop Motion function blocks use the same
bit definitions. Jogging uses some different bit definitions. Most of this data is for internal
use only; it is not of interest to the application program. The exceptions to this are bit 1
(Active output), which can be monitored for a Jogging function block, and bit 2 (Done
output), which can be monitored for the other function block types. See the function block
descriptions in this chapter for more information.

Bit

Description

Find Home, Go Home,
Blending, Stop Motion

Jogging

Least significant word

Execute input, previous execution

■

reserved

Active output

■

Done output

■

reserved

Error output

■

Warning output

■

Motion Started

reserved

Enable input, previous execution

■

Execute Triggered

reserved

Jogging, Enable Backward active = 1 reserved

■

Jogging, Enable Forward active = 1

reserved

■

Previous Enable Backward Value

reserved

■

Previous Enable Forward Value

reserved

■

Runtime Error Occurred

reserved

■

13-15

Not Used

reserved

Most significant word

Word

Error ID / Warning ID of the function block error that occurred. See next page.

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19.1.4

Error Codes and Warnings for Motion Features
(Hexadecimal)

The following error codes are used for the motion function blocks. These error codes appear

in word 2 of the function block’s 2 words of instance data, as described on the previous page.
They also appear in each function block’s Error ID out

put and in the channel, error

references: %AI002, 003, 004, and 005 for channels 1, 2, 3, and 4 respectively. The
application program should monitor error status using those references.

Error Code
(hex)

Error Description

Specified acceleration below minimum limit of 10 for channels 1, 2, 3 or below
minimum limit of 90 for channel 4

Specified acceleration above maximum limit of 1,000,000

Specified deceleration is below minimum limit of 10 for channels 1, 2, 3, or below
minimum limit of 90 for channel 4

Specified deceleration above maximum limit of 1,000,000

Specified Velocity is below minimum limit of 10

Specified Velocity is above maximum limit of 65000

Specified home offset is negative, which is not valid

Axis not configured for motion In the hardware configuration for HSC/PWM/PTO

settings, channel function should be selected as ‘Motion Support’ to be able to

initiate any motion command.

Axis busy with Ramping. User logic issued a motion command on a channel that
had Ramping already in progress.

Axis busy with Jogging.
Only one motion function block is allowed to be active at a time, but user logic has
issued another motion command while jogging command is still in progress.

Axis busy with Blending.
Only one motion function block is allowed to be active at a time, but user logic has
issued another motion command while blending command is still in progress.

Find Home cannot be started because Final Home velocity is greater than Find
Home velocity

Home switch Input is already on at the time of triggering Find Home command.

Go Home function block triggered without a previously successful Find Home
being completed.

Specified number of profiles is above the maximum limit of 4.

Specified number of profiles is below the minimum limit of 1.

Configured pulse count is less than the minimum limit of 2.

Axis busy with Find Home.
Only one motion function block is allowed to be active at a time but user logic has
issued another motion command while Find Home is still in progress.

If an active (not complete) function block instance is re-enabled while motion is still in progress, this condition is recorded as a

warning. If a different function block is enabled while motion is in progress, this condition is recorded as an error.

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Error Code
(hex)

Error Description

Axis busy with Go Home.
Only one motion function block is allowed to be active at a time, but user logic has
issued another motion command while Go Home is still in progress.

Motion function block issued before the axis was enabled (i.e. %Q0505,
506,507,508 bits are low on respective axis)..

No motion is in progress when Stop motion function block triggered.

Channel not configured to support motion function blocks. For the motion features
to be supported, the counter type should be either 4 Type A_32 or 1 Type A / 1 Type
B_32 counters on settings tab.

In continuous/rotary mode operation of the position register, high limit is less than
or equal to low limit.

Blending motion parameters array exceeds reference memory size. For example:
Each  profile  in  blending  contains  four  parameters  (acceleration,  deceleration,
velocity, and distance). Each parameter occupies two words. So, for each profile 8
words  of  memory  is  required.  Suppose  %AI120  is  assigned  for  blending  motion
parameters input. If the number of profiles is 4, then 32 words of memory, starting
from  %AI120,  needs  to  be  reserved  for  blending  motion  parameters.  But  %AI
memory can only be up to %AI128.

Stop motion function block is re-triggered before function block has finished
stopping motion. This is a warning.

Both enable forward, enable backward inputs are high on Jogging, which is invalid.

Motion cannot be started for the following reasons:
Either motion function block was triggered while Stop Motion function block is still
active (not complete), or the axis is blocked by the Stop Motion function block
(Execute input on Stop Motion function block is high). Axis error.

Stop Motion function block is issued while another motion function block is
pending to start on same axis. This error occurs if a motion function block (Jogging,
Blending, or Homing) is triggered on an axis and a Stop Motion function block is
triggered before motion can start on that axis.

More than one instance of Stop motion function block triggered on the same axis.

Motion stopped due to stop mode (PLC has transitioned from Run mode to Stop
mode), or power fail. Axis error.

Axis error present on the channel. Check %AI002, 3, 4, and 5 for axis error details
on respective channel. Axis errors can be cleared by a low-to-high transition of
output bits %Q489, 490,491, or 492 for channels 1, 2, 3, or 4 respectively.

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Axis and Function Block Errors

Of the errors listed above, errors 2B, 34, and 38 are axis errors. All other errors are function
block errors. If any axis error is present on an axis, no motion can be initiated on that axis by
any function block.

Clearing Axis Errors

Axis errors can be cleared by a low-to-high transition of output bits %Q489, 490, 491, or 492
for channel 1, 2, 3, or 4.

Axis errors are also cleared by any of the following:

•

clearing/downloading a hardware configuration

•

clearing/ downloading logic

•

clearing of all memory

•

clearing of initial values

After axis errors are cleared in %AI memory, motion can be started by any function block.

Operation of the Instance Registers

While the function block’s Enable input is receiving power flow, function block inputs are

stored to the Instance Registers, and function block outputs are updated continuously.

When the function block’s

Enable is not receiving power flow, the function block outputs

are not updated. However, they are still updated to the Instance Registers.

The next time Enable receives power flow, the output status data stored in the Instance
Registers is updated to function block outputs.

The Instance Register references should not be overwritten by user logic. Overlapping
reference addresses may cause erratic function block operation.

Motion Function Block Operation in PLC Run-Stop-Run
Transition or Loss of Power

If power is lost or if the Micro PLC goes to Linear mode while a motion function is being
executed, the motion stops immediately.

When power returns or when the Micro PLC goes to Run mode, the error 0x38 (see above)

is logged in the channel’s %AI memory refer

ence. The same error is generated on the

function block output when its Enable input receives power flow. Error 0x38 is an axis error;
no motion will occur on the axis until the error is cleared.

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19.1.5

Avoiding Abrupt Start/Stop of Motion

The following condition must be satisfied in order to avoid abrupt start/stop of motion:

n≥1

, where

If n<1, abrupt start/stop of motion can happen.

Example:

For the Find Home function:

Find Home Velocity = 1000

Final Home Velocity = 500

Acceleration = 10000

Deceleration = 10000

Offset = 0

With these parameters, the values for Final Home Velocity and Deceleration yield a value of

n=0.5, which does not satisfy the requirement n≥1. Instead of decelerating to home

position, the axis goes immediately to zero velocity. To avoid this, select values for Velocity,
Acceleration and Deceleration that satisfy the above condition.

19.2

Finding a Home Position

The Find Home function defines a Home (zero) position for the axis, relative to a physical
location on a machine. The location is represented by a Home Switch, which is connected
to a specific input on the Micro PLC. The Home Switch input must come from a normally
open contact. A normally closed contact cannot be used.

The Home Switch input is assigned to input reference %I002, %I004, %I006, or %I008
depending on the channel. The input reference cannot be used as a standard input when
the channel is used for Homing.

When a Find Home Cycle is requested, the following sequence is executed:

Figure 207

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After accelerating to the configured Find Home Velocity, the axis moves in the
specified direction until the Home Input signal is detected.

When the rising edge of Home Input signal is detected, the axis decelerates at the
deceleration rate and stops.

The axis then accelerates in the opposite direction at the Final Home Velocity until
the Home Input signal goes to 0.

Once the falling edge of the Home Input signal is detected (Home Input off as shown
above), the axis decelerates and stops.

At the falling edge of the Home Input, the CPU starts capturing the motor position
value. This continues until the motion stops and the axis makes a final move to the
Home switch or to the Home Offset.

Zero Home Offset: the axis accelerates to the Final Home velocity. It then
decelerates and stops at the edge transition of the Home Input. This is the Home
position. The position register is automatically zeroed upon completion of the Find
Home cycle.

Non-zero Home Offset: Depending on the value of the Home Offset and the motor
position captured by the CPU, the axis accelerates to the Final Home Velocity in
either forward or reverse direction. The axis moves until it decelerates again to reach
the Home Offset position. The position register is set to 0 when the axis reaches the
Home Offset position.

Figure 208

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19.2.1

Find Home Function Block

The application program uses the following function block to set up and control a Find
Home operation.

Figure 209

The channel’s Output Enable bit (for example, Q0505 for channel 1) must be set to 1 to use

this or any other motion function block on the channel. If the Output Enable bit is not 1, the
function will not execute, and a Channel Enable error will be reported.

When  the  Enable  input  receives  power  flow  and  the  Execute  input  transitions  to  1,  the
function  block  parameters  are  loaded.  If  the  parameters  are  not  valid,  a  warning  is
generated, and the function does not start. If the parameters are valid, the motion starts in
the direction (CW or CCW) specified by Axis Direction input, and the Active output is set to
1. Active returns to 0 when the function complete, or is stopped.

If the Enable input continues passing power flow after the motion completes, Find Home
can be restarted with the same parameters by again generating a low to high transition on
the Execute input. To execute the function block with different parameters, the Enable input
must stop passing power flow. After changing the parameter values, the function block can
be executed by again passing power flow to the Enable input and generating a low to high
transition on the Execute input.

The function block’s Enable output remains high as long as Enable Input is high.

If the Enable input stops receiving power flow while motion is in progress, the function

block’s Done output will not indicate when motion stops. In this case, the application
program should monitor the Done output bit (bit 2) at address +0 of the function block’s

assigned Instance data to determine when the motion is completed.

Transitions of the Execute input are only monitored while the Enable input is receiving
power flow. While the Enable input receives power flow, the Execute input is monitored for
a change in its status from the previous logic scan; if Enable and Execute transition in the
same scan, the transition of Execute is not detected. Therefore, the application logic must
not set both Enable and Execute either low or high in the same scan. If Enable and Execute
were made low in the same scan, the Find Home function block would still see the Execute
as high. If Execute and Enable were made high in the same scan, the Find Home function
block would not see the transition in Execute status and motion would not start.

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Stopping Find Home

Find Home can be stopped by:

•

Executing a Stop Motion function block, as described later in this chapter. This stops
any motion on the channel while leaving the channel active.

•

Disabling the channel by setting its High-Speed Counter enable output bit to 0. No
motion functions will operate on the channel while it is disabled.

CAUTION

To avoid abrupt starting and stopping of motion, the ratio of Velocity/Acceleration or

Velocity/Deceleration must be ≥ 0.1. For details, refer to page 420.

Inputs to the Find Home Function Block

Enable

The Enable input provides power flow to the function block.

Axis

A Constant representing the channel (1, 2, 3, or 4) on which Find Home will
be done.

Execute

Power flow to this input controls execution of the function.

Motion
Parameters

Starting address of 6-word reference location in AI, AQ, or R memory for

the motion speeds, which are specified in the channel’s configured units:

Words 1, 2

Homing acceleration:

10 to 1,000,000 for channels 1, 2, and 3

90 to 1,000,000 for channel 4.

Words 3, 4

Homing deceleration:

10 to 1,000,000 for channels 1, 2, and 3

90 to 1,000,000 for channel 4

Word 5, 6

Find Home velocity, from 15 to 65,000. . The velocity used
to reach Home position, the Find Home velocity is usually
high, to reach Home position quickly. The sum of velocities
on all channels must not exceed 65,000.

Final Home
Velocity

Dword variable (%AI, AQ, R) or Constant representing the velocity used
after the home switch is detected once. Final Home Velocity ranging from
15 to 65,000 is slower than the Find Home velocity, for greater precision in
arriving at the final Home Position.

Home
Offset

Real variable (%AI, AQ, R) or constant representing the Offset from the
Home Switch.

Axis
Direction
Input

Boolean variable (%I, Q, M, G, T) or Constant specifying the axis direction.
0 = Clockwise (CW), 1 = Counter-Clockwise (CCW). Note that the actual
direction depends on the field connections and drive settings.

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Outputs of the Find Home Function Block

Enable
output

Power flow output, passes power flow when it receives power flow from the
Enable input.

Axis
Direction
Output

Boolean variable (Q0005 to Q0024). The Micro PLC output point for which
direction  is  to  be  set.  0  =  clockwise,  1  =  counterclockwise.  The  actual
direction  depends  on  the  field  connections  and  drive  settings.    The
application  program  should  not  override  the  direction  output  during  the
Homing operation.

Done

Boolean variable (%I, Q, M, G, T) for the Find Home completion status. Goes
to 1 when motion is completed. If the Execute input is a pulse, rather than
staying continuously on, done remains 1/on for one scan after motion
completes.

Active

Boolean variable (%I, Q, M, G, T). Set to 1 when motion starts on the channel.
Resets to 0 when motion stops.

Error

Boolean variable (%I, Q, M, G, T) . Set to 1 if an error has occurred within
function block. See Error ID below.

Error ID

Word variable (%AI, AQ, R). If Error (ER) =1, this is an error ID. If Warning (WR)
=1, this is the Warning ID. See the list of error definitions on page 371.

Warning

Optional parameter. Boolean variable (%I, Q, M, G, T). Set to 1 when a
warning has occurred. See Error ID above. Warning is generated when the
same motion is triggered again while it is already in progress.

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If a Home Offset was set up during execution of the Find Home function, the Go Home
function causes the motor to move to the Home Offset position instead.

Figure 212

The number of pulses or the distance and the direction of motion are automatically
detected based on the Position Register value.

19.3.1

Go Home Function Block

The application program uses the following function block to set up and control a Go Home
operation:

Figure 213

The channel’s Output Enable bit (for example, Q0505 for channel 1) must be set t

o 1 to use

this or any other motion function block. If the Output Enable bit is not 1, the function will
not execute, and a Channel Enable error will be reported.

When the Enable input receives power flow and the Execute input transitions to 1, the
functio

n’s parameters are loaded. If the parameters are not valid, an error code is generated,

and the function does not start. If the parameters are valid, function execution starts and
sets the Active output to 1. Active returns to 0 when the function complete, or is stopped.

If the Enable input continues passing power flow after the function completes, Go Home
can be restarted with the same parameters by generating a low to high transition on Execute
input again. To execute the function block with different parameters, first stop motion and
then stop passing power flow to the Enable input. Then, change the parameter values. The
function block can then be executed by passing power flow to the Enable input and
generating a low-to-high transition on the Execute input.

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The function block’s Enable output remains high as long as Enable Input is high.

If the Enable input stops receiving power flow while motion is in progress, the function

block’s Done output will not indicate when motion stops. In this case

, the application

program should monitor the Done output bit (bit 2) at address +0 of the function block’s

assigned Instance data to determine when the motion is completed.

Transitions of the Execute input are monitored only while the Enable input is receiving
power flow. While the Enable input receives power flow, the Execute input is monitored for
a change in its status from the previous logic scan; if Enable and Execute transition in the
same scan, the transition of Execute is not detected. Therefore, the application logic must
not set both Enable and Execute either low or high in the same scan. If Enable and Execute
were made low in the same scan, the Go Home function block would still see the Execute as
high. If Execute and Enable were made high in the same scan, the Go Home function block
would not see the transition in Execute and motion would not start.

Stopping Go Home

Go Home can be stopped by:

•

Executing a Stop Motion function block, as described later in this chapter. This stops
any motion on the channel while leaving the channel active.

•

Disabling the channel by setting its High-Speed Counter enable output bit to 0. No
motion functions will operate on the channel while it is disabled.

CAUTION

To avoid abrupt starting and stopping of motion, the ratio of Velocity/Acceleration or

Velocity/Deceleration must be ≥ 0.1. For

details, refer to page 374.

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Inputs to the Go Home Function Block

Enable

The Enable input provides power flow to the function block.

Axis

A Constant representing the channel (1, 2, 3, or 4) on which Go Home will
be done.

Execute

Power flow to this input controls execution of the function. Rising edge is
detected to load the parameters and start execution of the function block.

Acceleratio
n

Dword variable or Constant representing the acceleration rate, from 10 to
1,000,000. 90 to 1,000,000 for channel 4.

Deceleratio
n

Dword variable or Constant representing the deceleration rate, from 10 to
1,000,000. 90 to 1,000,000 for channel 4.

Go Home
Velocity

Dword variable or Constant representing the velocity at which the Go
Home function is to be carried out. From 15 to 65,000. The sum of
velocities on all channels must not exceed 65,000.

Outputs of the Go Home Function Block

Enable
output

Power flow output, passes power flow when it receives power flow from
the Enable input.

Axis
Direction
Output

Boolean variable (Q0005 to Q0024). The Micro PLC output point for
which direction is to be set. 0 = clockwise, 1 = counterclockwise. The
actual direction depends on the field connections and drive settings. The
application program should not override the direction output during the
Homing operation.

Done

Boolean variable (%I, Q, M, G, T) for the GO Home completion status.
Goes to 1 when motion is completed and remains 1 until the next homing
cycle is started and Execute is continuously on. If the Execute input is a
pulse, rather than staying continuously on, Done remains 1/on for one
scan after motion completes.

Active

Boolean variable (%I, Q, M, G, T) for the Go Home Active status. 1 =
Homing in progress. 0 if motion is complete or has been stopped.

Error

Boolean variable (%I, Q, M, G, T) for the Go Home function block error
status. Set to 1 if an error has occurred within function block. See Error ID
below.

Error ID

Word variable. If Error (ER) =1, this is an Error ID. If Warning (WR) =1, this
is the Warning ID. See the list of error definitions on page 371.

Warning

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19.4.1

Jogging Function Block

The application program uses the following function block to set up and control Jogging.

Figure 216

The channel’s Output Enable bit (for example, Q0505 for channel 1) must be set to 1 to use

this or any other motion function block. If the Output Enable bit is not 1, the function will
not execute, and a Channel Enable error will be reported.

When the Enable input receives power flow, if no motion is active on the channel and either
Enable Forward (EF) or Enable Backward (EB) begins passing power flow, the function

’s

parameters are loaded. If the parameters are not valid, an error code is generated, and the
function does not start. If the parameters are valid and the Enable input is high, execution
starts in the forward (clockwise) direction if Enable Forward is high, or in the reverse
(counterclockwise) direction if Enable backward is high. The Active output is set to 1. Motion
starts at the specified input Acceleration value and continues at the specified input Velocity
until power flow is removed from EF or EB. The axis then decelerates at the Deceleration
value. Active returns to 0 when the function is fully stopped.

If both Enable Forward and Enable Backward pass power flow, an error is returned. When
either input subsequently goes low, motion starts in the other direction and the error clears
automatically.

If the Enable input continues passing power flow, Jogging can be restarted with the same
parameters by passing power flow to the EF or EB input again. To execute the function block
with different parameters, first stop motion. The Enable Forward or Enable Backward input
must stop passing power flow. After changing the parameter values, the application logic
can again pass power flow to the Enable Forward or Enable Backward input.

Enable Forward / Backward input level is not monitored unless the Enable input is receiving
power flow. The Enable Forward / Enable Backward inputs are level-triggered, not edge-
triggered.

The function block’s Enable output transitions to 0 automatically when EN input becomes

If the Enable input stops receiving power flow while motion is in progress, the function

block’s Active output will not indicate when motion stops. In this case, the application

program should monitor the Active output bit (bit 1) at address +0 of the function

block’s

assigned Instance data to determine when the motion is completed.

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Stopping Jogging

Jogging can be stopped by:

•

Executing a Stop Motion function block, as described later in this chapter. This stops
any motion on the channel while leaving the channel active.

•

Disabling the channel by setting its High-Speed Counter enable output bit to 0. No
motion functions will operate on the channel while it is disabled.

CAUTION

To avoid abrupt starting and stopping of motion, the ratio of Velocity/Acceleration or

Velocity/Deceleration must be ≥ 0.1. For details,

refer to page 374.

Inputs to the Jogging Function Block

Enable

The Enable input provides power flow to the function block.

Axis

A Constant representing the channel (1, 2, 3, or 4) on which Jogging will
be done.

Enable
Forward

If the Enable input is passing power flow, power flow to EF enables
forward motion (clockwise) of the specified axis and starts the Jogging
operation. If Jogging is already in progress, removing power flow to EF
stops motion.

Enable
Backward

If the Enable input is passing power flow, power flow to EB enables
backward motion (counter-clockwise) of the specified axis and starts the
jogging operation. If Jogging is already in progress, removing power flow
to EB stops motion.

Acceleration Dword variable (AI, AQ, R) or Constant representing the jogging

acceleration rate, between 10 and 1,000,000 for channel 1 to 3 and 90 to
1,000,000 for channel 4.

Deceleration Dword variable (AI, AQ, R) variable or Constant representing the jogging

deceleration rate, between 10 and 1,000,000 for channel 1 to 3 and 90
to 1,000,000 for channel 4.

Velocity

Dword variable (AI, AQ, R) or Constant representing the velocity rate,
between 15 and 65,000. The sum of velocities on all channels must not
exceed 65,000.

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