ElmoMC SimplIQ Analog Servo Amplifiers-Piccolo Installation - Manual (Page 23)

Piccolo Installation Guide Servo Control Operation
MAN-PICIG (Ver. 2.301)
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23
Chapter 4: Servo Control Operation
4.1. Current Command Input
The Piccolo has a single differential input. The input operating voltage range is ± 3.75 V,
meaning that a 3.75 V signal will result in a fully rated peak current. The current limit circuits
will override this signal if the peak duration exceeds 2.7 seconds and/or the required current
exceeds the values set by the ECLC and ECLP signals. If the input command voltage exceeds
3.75 V, input scaling must be implemented by adding a pair of external resistors, according to
the following formula:
R
in (KΩ)
= (5.33 * V
in
) - 20
Be careful not to apply input voltage above the maximum allowed input voltage as this will
cause the input operational amplifier to operate beyond its limits (+20 V) and in extreme cases,
may even damage it.
4.2. CFM
The amplifier is equipped with a current feedback multiplier (CFM). Connecting pin J1/10 to
J1/8 multiplies the signal of the current feedback by 2 and consequently causes the following
changes to occur:
• Current gains are divided by 2.
• Current monitor is multiplied by 2.
• Current limits are divided by 2.
This function should be activated whenever the rated current and the peak current of the
motor are less than 50% of the amplifier rated continuous and peak limits, respectively.
Continuous
Current
Limit Peak Current
Limit Current
Gain(A/V) Current
Monitor
(V/A) Differential
Input
Impedance
Without CFM Ic Ip Ip/3.75 3.9/Ip 40 kΩ
With CFM Ic/2 Ip/2 Ip/7.5 7.8/Ip 40 kΩ
Table 7: CFM Effects
• The default (pin J1/10 left open) is the low current feedback.
• For permanent selection, a simple short is recommended.
• For remote selection, the scheme in Figure 5 should be used.