Remote Control Basics > SCPI Command Structure > Responses to Queries
Responses to Queries

A query is defined for each setting command unless explicitly specified otherwise. It is formed by adding a question mark to the associated setting command. According to SCPI, the responses to queries are partly subject to stricter rules than in standard IEEE 488.2.

  • The requested parameter is transmitted without a header.
    Example:HCOP:PAGE:ORI?, Response: LAND
  • Maximum values, minimum values and all other quantities that are requested via a special text parameter are returned as numeric values.
    Example:SENSe:FREQuency:STOP? MAX, Response: 3.5E9
  • Numeric values are output without a unit. Physical quantities are referred to the basic units or to the units set using the Unit command. The response 3.5E9 in the previous example stands for 3.5 GHz.
  • Truth values (Boolean values) are returned as 0 (for OFF) and 1 (for ON).
    Example:
    Setting command: HCOPy:DEV:COL ON
    Query: HCOPy:DEV:COL?
    Response: 1
  • Text (character data) is returned in a short form.
    Example:
    Setting command: HCOPy:PAGE:ORIentation LANDscape
    Query: HCOP:PAGE:ORI?
    Response: LAND
  • Invalid numerical results
    In some cases, particularly when a result consists of multiple numeric values, invalid values are returned as 9.91E37 (not a number).

 


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