QTech Data Systems Q23 I__O Expansion Module - Manual (Page 4)

DATRAN II eXcel - Q23 Quick Start Guide – v2.0 – September 2010
RTU
+ Supply
Dig Out 1
RTU
Tx
Anl In 1
+
Digital Outputs
As with the Digital Inputs, the module Digital Outputs are designed to be easily interfaced
with relays and contactors.
The module has 8 Digital Outputs in total. The first four are located on the front panel
adjacent to the Digital Inputs and have LED indicators to show if the output is active or not.
The second four Digital Outputs are located on the underside of the module next to the
power connector, labeled “Aux Out”.
The Digital Outputs work as “Current Sinks”. This means that when
they are turned on, they will be connected to power supply ground,
allowing current to flow into the output terminal to ground. When in the
“OFF” state, they have a high impedance to ground and will float up to
+ Supply.
To use a digital output with a relay, wire as shown in the diagram
opposite:
Analog Inputs
The module has 6 analog channels. All analog channels are independently capable of
operation as either 0-20 mA, 4-20 mA, 0-5 V or 0-10 V. In addition to this, channels 5 and
6 are independently able to be configured as either inputs or outputs. The module comes
factory shipped with all analog channels configured as 4-20 mA inputs. For details on how
to reconfigure them, refer to the DATRAN II eXcel Users Guide.
For all analog inputs, the current return path is via the ground of the module power supply.
It is important to understand the implications of this when wiring certain analog devices to
the module, as detailed below.
The LED’s adjacent to each Analog Input show the status of the signal the eXcel is
receiving. If the LED is off, it means the input signal is zero, or under-range. When the
LED is on, it indicates the signal is within the measuring range that the input has been
configured for. If the LED is flashing, it shows the signal is over-range.
Loop Powered Devices
“Loop-Powered”, or “2-Wire” devices derive their power supply from the current flowing in
the loop itself. It is important to make sure that any device is rated to operate at the voltage
that will be available to it taking into account that the eXcel Analog Input will drop 5 v
across it at 20 mA loop current.
For example: If the system is being powered from 13.7 VDC, the
analog transducer will only have a maximum of 8.7 volts available to it
for its power supply.
To wire a “2-Wire” device, refer to the diagram opposite:
Separately Supplied Devices
“Separately Supplied”, or “4-Wire” devices are analog transmitters that
have a separate power supply from the analog signal loop. If suitable,
these devices can be powered from the eXcel power supply. If the
eXcel power supply is not suitable, the analog sensor can be powered
from a separate power supply as long as the grounds of both the eXcel
and the other power supply are connected together.
Wiring of a 4-Wire device is as shown:
RTU
Tx
Anl In 1
G