Beckhoff EM7004, Documentation

Page: 17 / 130

Product overview
EM7004 17 Version: 2.0
Sample: Limitation of the output range from -5 V to +5 V, calculation of the user
scaling GAIN factor
Y
A
= 16383
dec
corresponds to the desired upper limit value of +5
V
Y
H
= 32767
dec
corresponds to the upper limit value of +10 V
B
W
= 0
dec
corresponds to the offset of the user scaling
Y
A
= Y
H
x A
W
x 2
-16
+ B
W
Û (Y
A
- B
W
) / (Y
H
x 2
-16
) = A
W
(16383 - 0) / 32767 x 2
-16
= A
W
= 32767
Calculation of the GAIN value for an upper limit value of +5 V
(corresponds to a lower limit value of -5 V through cancelling the sign)
corresponds to the user scaling gain factor (factor 0.5)
Sample: Shifting of the output range from -3 V to +10 V, calculation of the user
scaling OFFSET value
Y
A
= (- 9831
dec
) corresponds to the desired lower limit value of -3 V
Y
H
= (-32769
dec
) corresponds to the lower limit value of -10 V
A
W
= 65536
dec
corresponds to the gain factor of the user scaling (factor 1)
Y
A
= Y
H
x A
W
x 2
-16
+ B
W
Û Y
A
- Y
H
x A
W
x 2
-16
= B
W
(- 9831) - (- 32769 x 65536 x 2
-16
)
= B
W
= 22938
Calculation of the OFFSET value for the shifting of the lower limit value
to -3 V
corresponds to the offset value of the user scaling of +7 V
Note
OFFSET value
Shifting of the output value through the OFFSET is linear up to the lower (- 10 V) or upper
limit value (+ 10 V).
User-specific output value (user default output)
The analog output value can, e.g. in the case of a failure of communication with the controller, be set to a
user-specific value. The objects
0x8020:06 [
}
97] (channel 1), 0x8030:06 [
}
97] (channel 2), 0x8040:06
[
}
97] (channel 3), 0x8050:06 [
}
97] (channel 4) activate this option (value: TRUE); the output values are
determined with the objects 0x8020:13 [
}
97] (channel 1), 0x8030:13 [
}
97] (channel 2), 0x8040:13 [
}
97]
(channel 3), 0x8050:13 [
}
97] (channel 4). If this function is disabled (value of object 0x8020:06 [
}
97]
(channel 1), 0x8030:06 [
}
97] (channel 2), 0x8040:06 [
}
97] (channel 3), 0x8050:06 [
}
97] (channel 4) is
FALSE), the manufacturer default value (0V) is output.
If the watchdog timer is deactivated (value of object
0x8020:05 [
}
97] (channel 1), 0x8030:05 [
}
97]
(channel 2), 0x8040:05 [
}
97] (channel 3), 0x8050:05 [
}
97] (channel 4) is TRUE), no default value is
output.
PLS function (Programmable Limit Switch)
The PLS function enables a certain value ("PLS output data", object 0x80A2 [
}
111] ) to be assigned to the
digital outputs when the assigned encoder ("Encoder as PLS source", object 0x80A0:01 [
}
98] ) has reached
a particular switch value ("PLS switch value", object 0x80A1 [
}
111] ). Object 0x80A0:11 [
}
98] ("output
mask") is used to specify which of the digital outputs are allocated to the PLS function.