Page 8
IronHorse GSDA-CM-8 User Manual – 1st Ed. Rev. A – 10/15/19
Voltage Source Input:
By selecting the voltage source type, the GSD8 drive will track a rapidly changing analog input signal.
The GSDA-CM-8 samples the analog input signal at the rate of 50 milliseconds. Intended primarily as
a feedback signal, replacing an encoder feedback signal or a leader signal when in a master/follower
application; voltage values tracked in this mode are not stored in non-volatile memory and so are
lost when power to the drive is turned off. This should be considered when choosing this source
type. Though designed for 0 to +5 VDC signals, other positive voltage ranges such as 0 to +10VDC
can be accommodated through the use of an external voltage divider circuit. Input impedance is
approximately 15.4 kohms.
DC
GSDA-CM-8, Pin 7
Analog Input (0 to 5 VDC)
GSDA-CM-8, Pin 6
Signal Common (GND)
V
s
V
out
R1
R2
+
Voltage Divider - Resistor Values
Formula: V
out
= V
s
x R2/(R1+R2)
Where:
• V
out
= Desired output voltage
• V
s
= Source voltage
• R1 = Resistance of the 1st resistor in ohms
• R2 = Resistance of the 2nd resistor in ohms
V
s
R1*
R2*
V
out
Watts
0-10
20
20.00
0-5
0-0.5
0-12
24
17.14
0-5
0-0.5
0-14
28
15.56
0-5
0-0.5
0-16
32
14.55
0-5
0-0.5
0-18
36
13.85
0-5
0-0.5
0-20
40
13.33
0-5
0-0.5
* 0.5 W
4 to 20mA Current Source Input:
A 4 to 20 mA current source type is tracked by the GSD8 drive at a 50 millisecond sample rate; in the
same way as the voltage source signal type. The 4 to 20 mA range of the signal is fixed such that values
less than 4mA and greater than 20mA are treated as minimum and maximum values respectively. The
use of a milliamp signal requires an external resistor, typically 250 ohms, with a precision of 0.1%.
Resistors with higher precision values of 1% or 5% can affect accuracy and contribute to drift errors.
Proper wiring and the correct resistance value are addressed in subsequent pages.
Analog Source Signal Assignment
An analog input signal connected to the GSDA-CM-8 can be assigned to one of several different
functions. With the exception of the “Frequency Generator”, there is no restriction on what type of
signal source can be assigned to a given function. There are six possible analog input signal functions.
They are:
•
NONE (Analog Input Ignored)
•
Target “Speed” Setting
•
Percent of Target Setting
•
Frequency Generator Rate
•
Main “Tach” signal (replaces regular pickup)
•
Leader “Tach” signal (replaces regular signal)
The possible types of analog input sources for each destination are shown below:
Analog Input Sources
Destination
Pot
Voltage
Current
Target Speed
Y
Y
Y
% of Target
Y
Y
Y
Freq. Gen.
Y
N
N
Main “Tach”
Y
Y
Y
Leader “Tach”
Y
Y
Y
