2 Installation
2.5 Connecting the inputs
40
Control Relay easy800
11/11 MN04902001Z-EN
www.eaton.com
2.5.2 Connecting analog inputs
All easy800 standard devices with a 24 V DC supply voltage are provided
with analog inputs. On the easy800 standard from device version 02, it is
also possible to connect the EASY406-DC-ME and EASY411-DC-ME DC
expansion units (
section , “Connecting DC inputs of the EASY4..-DC-ME
▶
Use screened or twisted pair cables.
▶
Keep signal cables as short as possible and not longer than 10 m.
▶
With short cable lengths ground the shield of the signal cables at both
ends with a large surface area connection. With longer signal cables, the
shield should only be grounded at one end, on the side of the easy800
standard or expansion unit. Otherwise compensation currents between
both grounding points may flow, leading to the interference of analog
signals.
▶
Lay signal cables separately from heavy current cables.
▶
Connect inductive loads to be switched via the easy800 standard device
outputs to a separate power feed, or use a suppressor circuit for motors
and valves. If loads such as motors, solenoid valves or contactors and
easy800 standard are operated with the same power feed, switching
may give rise to interference on the analog input signals.
▶
Ensure a galvanic connection of the reference potential as described
below.
▶
Avoid the operation of the easy800 standard or expansion unit on an
ungrounded power supply.
Connecting the analog inputs of the
800 standard
You can read analog voltages in the range 0 to 10 V via the inputs I7, I8, I11
and I12 of the easy800 standard DC version.
The signal has a 10-bit resolution, value range 0 - 1023.
The following therefore applies:
•
I7 = IA01
•
I8 = IA02
•
I11 = IA03
•
I12 = IA04
The analog voltage inputs can also be used as digital inputs.
The following circuits are examples of using the analog value measuring via
inputs of the easy800 standard DC version.
DANGER
Analog signals are more susceptible to interference than digital
signals, so that the signal cables must be laid and connected
more carefully. The measures described below must be
adhered to in order to prevent any deviations in analog values.
An incorrect connection can lead to unwanted switching states.
