GS-C200 datasheet(26/31 Pages) STMICROELECTRONICS

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COMPLEX MOVEMENTS SYNCHRONIZATION

In many applications the synchronization of several

movements is quite often required and the GS-C

allows this function to be easily implemented either

by using the Step Enable input or the User in-

put/output pins. In fig.13A and fig.13B the block

diagrams relative to the two solutions are reported.

The solution A is the simplest but it has some

limitations, i.e. it can be used only when the whole

system has to move synchronously. The solution B

is more complex but also more flexible and it allows

the program to control where and when the syn-

chronization must be implemented.

THE START-STOP SPEED (S command)

SELECTION

A typical Start-Stop curve (as shown on Fig. 14),

shows that for a given driving voltage and phase

current, the highest drive frequency allowed at the

start (Pull-In Rate) is much lower than the one

allowed for the stop (Pull-Out Rate) and that both

are influenced by the load value. Of course the

higher the current level the higher is the available

torque, and the system can be started at a greater

speed. Asignificant increase of the start-stop speed

is obtained when the supply voltage is increased

but in both cases the problem related to the me-

chanical resonance must be considered. It is advis-

able to maintain a significant safety margin against

the system torque limit in order to avoid any prob-

lem due to the friction variation. A commonly ac-

cepted rule fixes the Start-Stop speed equal to the

50% of the maximum theoretical value reported on

the motor data sheet; this takes into account fric-

tion, load inertia variations as well as motor pa-

rameter differences and power supply fluctuations.

Figure 13. Complex Movements Synchronization

Figure 14. Start-Stop Characteristic.

SLEW SPEED (T command) SELECTION

The Slew speed is roughly determined by the load

and it can be evaluated by using the following

relation:

⋅ L

6000

⋅ t =

⋅ N

where

F = Strength in Pounds

T = Torque in Ounce/Inch

L = Length in Inches

N = Speed in turn/min.

t =

Time in seconds

GS-C200 / GS-C200S

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