Allen-Bradley Studio 5000 Logix Emulate User Manual

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Chapter 6

Multi-Axis Coordinated Motion Instructions

516 Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018

If a MCD or MCCD is executed (indicated by status bit going IP), the CalculatedDataAvailable (CDA) bit will be cleared. The

Calculated Data for the move will be recomputed using the new dynamics parameters. Only those items of the Calculated Data

array whose Event Distance hasn’t been reached yet are recomputed; other items are left as they are. Consequently, all Calculated

Data array items contain valid information after the move is completed. The CDA bit will be set again when computations are

complete, The Calculated Data that is recomputed will be measured from the original MSP to the Event Distance point using the

new dynamics parameters as changed by the MCD or MCCD instruction, not from the point of the MCD or MCCD. Note that if the

MCD changes the speed to 0, the Event Distance will not be recomputed; the CDA bit will be cleared and stay cleared. The Event

Distance will however be recomputed if a second MCD or MCCD is issued to restart the motion. The recomputed Calculated Data

will include the duration of the stopped motion.

If the Event Distance is set to 0, the Calculated Data will be set equal to the position that equals the length of the move. This may

be one or two coarse update periods before the PC bit is set because of an internal delay. The end position is typically achieved in

the middle of a coarse update period that adds up to one additional coarse update period to the delay. Therefore, if the master is

moved a distance equal to the Calculated Data, you must wait up to 2 iterations more for the PC bit of the slave move to be set.

Note that there is a special consideration for the rare case of an overshoot when an MCD or MCCD is done close to the moves

endpoint. For this case, when the Event Distance is 0, the returned Calculated Data will include the overshoot distance traveled,

since the master will have to traverse this amount for the move to finish. For non-zero Event Distances, the overshoot distance will

not be included.

A status bit (CalculatedDataAvailable) in the existing motion instruction status word has been defined to indicate that all of the

requested data for the specified Event Distance array elements has been returned in the corresponding Calculated Data array

elements. Only one status bit is used to indicate all Calculated Data is available.

Once set, this bit may later be cleared based on a number of different conditions including, but not limited to, an MAS, MCS being

executed

Note that Calculated Data is only set once in the instruction queue or planning process. It is not updated as the move occurs to

reflect distance to go. It is updated for a change dynamics, however.

For coordinated moves, the CDA status bit is set when the Calculated Data is available. In general, for a blending termination type

(TT2, 3, 6) or follow contour termination type (TT4, 5) you will not see CDA for move N until move N+1 is put in the queue. For a

non-blended termination type (TT0, 1), the CDA will be seen right after the move is put into the queue. You will not see the CDA

bit if a move sequence is terminated by a blending or follow contour termination type. That is, you must terminate a blending

sequence by a TT0 or TT1. The TT0 or TT1 has to be in the motion sequence, but does not have to be in the queue together with a

blending sequence. The move with a TT0 or TT1 can be placed in the queue when space becomes available after the last blended

move.

The CDA bit will not be set for any move that Event Distance is not specified, that is, where the Event Distance parameter in the

instruction is zero.

The default value for versions when bringing old systems forward (earlier than v20) is 0, signifying that there is no Event Distance

array.

Calculated Data Example 1

Event Distance array = [11, 22, -5, 23, 44]

Calculated Data array = [f(11), f(22), -1 ,f(23)]

Where f is the calculated data function.

Tip:

•

The 44 is ignored because it is the fifth element in the Event Distance array.

Nothing is returned in the corresponding 5th array element of Calculated Data

array.

• A -1 is returned in the third element of the Calculated Data array because the

corresponding Event Data Array element is negative.

Calculated Data Example 2

Assume that the master axis is at a position of 2.0. The slave is programmed to an

incremental value of 15.0 with a

Master Lock Position at 8.0. The Event Distance is set to 0.0, which means that

we want the total

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Allen-Bradley Studio 5000 Logix Emulate Specifications

General

Type	Emulation Software
Supported Platforms	PC
Operating System	Windows
Compatible Controllers	ControlLogix 5570, ControlLogix 5580, CompactLogix 5370, CompactLogix 5480
Integration	Integrated with Studio 5000 environment
Works with Studio 5000 Logix Designer	Yes
Programming Languages	Ladder Logic, Function Block Diagram, Structured Text, Sequential Function Chart
Communication Protocols	EtherNet/IP
Functionality	Controller Emulation
Purpose	Testing and Debugging
Use Case	Program development, testing, training, and troubleshooting without physical PLC hardware