set_units - 2022.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

Document ID
Release Date
2022.1 English

Set units for checking


set_units [‑capacitance <arg>] [‑current <arg>] [‑voltage <arg>]
    [‑power <arg>] [‑resistance <arg>] [‑altitude <arg>] [‑quiet]


Name Description
[-capacitance] Capacitance unit in farad. Valid values are from kF-fF. Default: pF
[-current] Current unit in ampere. Valid values are from kA-fA. Default: mA
[-voltage] Voltage unit in volt. Valid values are from kV-fV. Default: V
[-power] Wattage unit in watts. Valid values are from kW-fW. Default: mW
[-resistance] Resistance unit in ohm. Valid values are from kOhm-fOhm. Default: ohm
[-altitude] Altitude in metric or standard units. Valid values are meters and feet. Default: meters
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution




This command specifies the default units to be assumed when the design is analyzed. Specifically, the -current, -voltage, -power, and -resistance options impact the values returned by the report_power command.

The set_units command can be used multiple times to define and redefine units. If set_units includes a previously set unit value, the unit is redefined.

Note: This command operates silently and does not return direct feedback of its operation.


-capacitance <arg> - (Optional) Specify the unit of capacitance in Farads. Valid values range from kilofarads (kF) to femtofarads (fF). The default unit of capacitance is picofarads (pF).

-current <arg> - (Optional) Specify the unit of current in amperes. Valid values range from kiloAmps (kA) to femtoAmps (fA). The default unit of amperes is milliAmps (mA).

-voltage <arg> - (Optional) Specify the unit of voltage in Volts. Valid values range from kilovolts (kV) to femotovolts (fV). The default unit of voltage is Volts (V).

-power <arg> - (Optional) Specify the unit of power in watts. Valid values range from kilowatts (kW) to femtowatts (fW). The default unit of power is milliwatts (mW).

-resistance <arg> - (Optional) Specify the unit of resistance in ohms. Valid values range from kilo-ohm (kOhm) to femto-ohm (fOhm). The default unit of resistance is ohms (Ohm).

-altitude [ meters | feet ] - (Optional) Specify the unit of altitude as meters or feet. The default unit is meters.

-quiet - (Optional) Execute the command quietly, returning no messages from the command. The command also returns TCL_OK regardless of any errors encountered during execution.
Note: Any errors encountered on the command-line, while launching the command, will be returned. Only errors occurring inside the command will be trapped.
-verbose - (Optional) Temporarily override any message limits and return all messages from this command.
Note: Message limits can be defined with the set_msg_config command.


Specify that voltage should be in millivolts and all values should use three digits

set_units -voltage mV

The following example changes the default unit for current to Amperes:

set_units -voltage kV -current A
Note: The second example of set_units redefines the Voltage units defined in the first example, as well as defining the units for current.