Bosch 6000 User's Guide download pdf (Page 236)

Chapter 6. Following

221

Triangular

Slave Moves

D =

peak

* FOLMD

where:

FOLMD = Master distance

peak

= Peak ratio reached during move

D = Total slave distance

NOTE

☞

Profile depicts

ratio vs. distance.

max

Ratio

Distance

Triangular profile if:

D < 1/2 D

MAX

peak

FOLMD

Distance

Calculation

Example

In the example below, the desired travel during constant ratio is already contained in numeric

variable #1 (VAR1), and may have been read from thumbwheels or a DATA command. The

corresponding slave move distance (D) and FOLMD are calculated as shown:

VAR2=2 ; Desired slave travel during accel and decel combined

VAR3=2 * VAR2 ; Required master travel during these ramps

VAR4=VAR1 + VAR2 ; Move distance is constant ratio portion plus ramps

VAR5=VAR1 + VAR3 ; Master travel for entire slave move

FOLMD(VAR5) ; Establish calculated master travel

D(VAR4) ; Establish calculated slave travel

GO1 ; Make desired slave move

Similar calculations may be done for a series of continuous move ramps to ratios, separated by

GOWHEN for master cycle positions. These ramps may be repeated in a loop to create a

continuous cyclical slave profile.

Beware of

Roundoff Error

(Scaling only)

Some potential for roundoff error exists if the scaling of a move distance or master distance by

SCLD and SCLMAS does not result in an integer number of steps. Some additional care must

be taken in the segment by segment construction of profiles using ramps to continuous ratio.

The 6000 controller maintains a slave position command which is calculated from the

commanded constant ratios, the ramps to the new ratios, and the master travel over which

these take place. At the end of each ramp or constant ratio portion, this commanded position

is calculated to the nearest integer slave step. If the ratios and master travel result in a non-

integer slave travel for a segment, the fractional part of that segment's calculated travel will be

lost. In a cyclical application, repeated truncations could build up to a significant error. This

may be avoided through careful attention to design of the profile.

Using Other Features with Following

The 6000 controller has many features that may be used in the same application as its

Following features. In some cases, having configured an axis as a slave with the FOLMAS

command will affect, or be affected by, the operation of other features, as described below.

Setups used by

FOLMAS

(Steppers Only)

The FOLMAS command uses the drive resolution (DRES), the velocity range (PULSE), and the

choice of motor step positioning or encoder step positioning (ENC) data to configure an axis

as a slave. If encoder step positioning is chosen (ENC1) , the encoder resolution (ERES) data

is also used. In order for this data to be used correctly, these commands must

be given before FOLMAS. These commands are not allowed after FOLMAS is

given. After FOLMAS is executed, the MC command may be used to change from

incremental to absolute positioning and back, but a change to encoder or motor step

positioning (ENC) is not allowed.

S (Stop) & K (Kill)

Commands

Stop (S) and Kill (K) commands cause the slave to do a non-Following decel, even if the slave

is in Following mode. A stop or a kill, buffered or immediate, will clear a pending GOWHEN

condition (clears AS bit #26).

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Bosch 6000 User's Guide Page 236

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