describe - 2022.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

Document ID
Release Date
2022.1 English

Describe an HDL object (variable, signal, wire, or reg) by printing type and declaration information


describe [‑quiet] [‑verbose] <hdl_object>


The description of the selected objects.


Name Description
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution
<hdl_object> The hdl_object or hdl_scope to describe



Describe an HDL object (variable, signal, wire, or reg) by printing type and declaration information, as well as path, and file information for the HDL source of the specified objects.

Tip: The describe command works for a single HDL object. Use the report_objects command for a brief report on multiple HDL objects.

HDL objects include HDL signals, variables, or constants as defined in the Verilog or VHDL test bench and source files. An HDL signal includes Verilog wire or reg entities, and VHDL signals. Examples of HDL variables include Verilog real, realtime, time, and event. HDL constants include Verilog parameters and localparams, and VHDL generic and constants.

The command returns the description of specified HDL objects, or returns an error if it fails.


-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.
<hdl_object> - (Required) Specifies a single HDL object to describe.
Note: Objects can be specified by name, or returned as objects by the get_objects command.


The following example shows how the objects description depends on the scope of the current simulation:
current_scope testbench
describe leds_n
    Signal: {leds_n[3:0]}
    Path: {/testbench/leds_n}
    Location: {File "C:/Data/ug937/sim/testbench.v" Line 9}
current_scope dut
describe leds_n
    Port(OUT): {LEDS_n[3:0]}
    Path: {/testbench/dut/LEDS_n}
    Location: {File "C:/Data/sources/sinegen_demo.vhd" Line 42}