Beckhoff EP3356-0022, Документация

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Commissioning/Configuration
EP3356-0022 51 Version: 1.4
5.7 Voltage measurement
The EP3356 principally offers a 2-channel voltage measurement on one box with 2 very different measuring
ranges of ±25 mV and ±12 V nominal voltage. The load on the one connected strain gauge can be calculated
from the two simultaneously measured voltages; the EP3356 already performs this calculation in the box and
thus represents a 1-channel box in the sense of load calculation.
The following applies to the individual channels:
• Channel 1:
◦ Typical measuring range approx. -13.5 V to 0 to +13.5 V (equivalent to process value
0x80.00.00.00 to 0 to 0x7F.FF.FF.FF)
◦ Nominal measuring range: -12 V... 0 ... +12 V
◦ max. permissible voltage -U
D
vs. +U
D
: ±13.5 V
◦ Measuring error < ±0.1 % of the full scale value, 50 Hz filter active
• Channel 2:
◦ Typical measuring range approx. -27 mV to 0 to +27 mV (equivalent to process value
0x80.00.00.00 to 0 to 0x7F.FF.FF.FF)
◦ Nominal measuring range: -25 mV... 0 ... +25 mV
◦ max. permissible voltage -U
ref
vs. +U
ref
: ±27 mV
◦ Measuring error < ±0.1 % of the full scale value, 50 Hz filter active
• in strain gauge mode the connected strain gauge guarantees that no impermissibly high potential
differences arise inside and outside the circuit.
In the standard setting the EP3356 operates as a 1-channel strain gauge monitor with the process image
[ } 54] ; the box can be switched to 2-channel voltage measurement by changing the process data. See the
notes on the process image regarding this. If the EP3356 is not used as a load measuring box, but rather as
a 2-channel analog input measuring box, the following must be observed:
• The CoE settings are to be found for:
◦ Channel 1: objects under 0x8010:xx [
}
64]
◦ Channel 2: objects under 0x8020:xx [ } 64]
◦ the strain gauge objects under x8000:xx have no function. Exception: the averager ( 0x8000:03
[
}
66] ) can also be used in voltage measuring mode and applies to both channels
simultaneously.
• Self-calibration is not possible and useful.
• The two analog channels are not calibrated by the manufacturer, since this is not required for the
relative measurement in strain gauge mode. This means, for example, for channel 1 with a nominal
measuring range of ±12 V or a typical measuring range of ±13.5 V, that the maximum measured value
0x7F.FF.FF.FF can be output by one terminal/box for example as 13.4 V and by another as 13.6 V. If
terminals/boxes output identical process values for identical applied voltages, meaning that they are
exchangeable, each channel must be calibrated by the user by making settings for each channel in the
CoE. The user calibration (CoE
0x80n0:17 [ } 64] [offset], 0x80n0:18 [ } 64] [gain]) or the user scaling
(CoE 0x80n0:11 [ } 64] [offset], 0x80n0:12 [ } 64] [gain]) can be used for this.