Analog Input Voltage And Current Mode; Analog Input Behavior; Analog Input Zero Scale And Full Scale Values - Siemens US2:9810T24V User Manual

9810 series - User manual

Analog input voltage and current mode

You can set the analog input's mode for voltage or current sensing.
In current mode, the analog inputs have a low input resistance while the meter is powered on, and
a high input resistance when the meter is powered off. In voltage mode, the analog inputs have a
high input resistance regardless of whether the meter is powered or not.
NOTE: When unpowered, your meter's analog inputs act like they are in voltage mode (high
input resistance).
When connected to a current output transducer, this high resistance can create a high voltage.
Standard (i.e., 4–20 mA) current transducers have open circuit protection and can handle a high
input resistance; however, if non-standard transducers are used high voltages may be generated.
Your meter's analog input has circuitry to limit this voltage, but it may not be sufficient with a very
high-power current source.
EQUIPMENT DAMAGE
Failure to follow these instructions will result in equipment damage.
• Ensure the analog input is configured for the correct voltage or current mode before
connecting or activating the current transducer.
• Do not exceed the device's ratings for maximum limits.

Analog input behavior

Analog inputs may show a value below zero scale if an open circuit is detected on the input port.

Analog input zero scale and full scale values

In most cases the output range of the sensor feeding the analog input matches the hardware
limits of your meter's analog input port. In that case, the analog input's zero scale and full scale
values are the same as the sensor's represented range. For example:
Analog sensor
0–50 psi represented by a
4–20 mA signal
0–50 psi represented by a
0–20 mA signal
1
Analog I/O option module must have firmware version v1.2 or later.
7EN05-0390-08
NOTICE
Meter's analog input signal
4–20 mA analog input range
Input value: 12 mA
0–20 mA analog input range
Input value: 12 mA
Analog input register values
Full scale = 50 (psi)
Zero scale = 0 (psi)
Scaled value: 25 (psi)
Full scale = 50 (psi)
1
Zero scale = 0 (psi)
Scaled value: 30 (psi)
Inputs/Outputs
132