A measurement system comprising: a plurality of pressure measurement apparatuses configured to measure pressure at a measurement timing designated by a trigger signal; wherein each pressure measurement apparatus in the plurality of pressure measurement apparatuses comprises: a controller configured to execute pressure measurement processing at the measurement timing designated by the trigger signal; a first input unit connected to an internal trigger generator ; a second input unit connected to an input terminal for receiving an input from an external apparatus; a trigger input switching unit configured to switch an input source of the trigger signal between the internal trigger generator and the external apparatus by selectively switching between the first input unit and the second input unit based on a control signal from the controller ; and an output unit connected to an output terminal and configured to output the trigger signal from the input source via the output terminal; wherein the plurality of pressure measurement apparatuses is connected in a daisy chain such that the output terminal of a first pressure measurement apparatus in the plurality of pressure measurement apparatuses is connected to the input terminal of a second pressure measurement apparatus in the plurality of pressure measurement apparatuses , and characterized in that the output terminal of the second pressure measurement apparatus in the plurality of pressure measurement apparatuses is connected to the input terminal of a third pressure measurement apparatus in the plurality of pressure measurement apparatuses . a plurality of pressure measurement apparatuses configured to measure pressure at a measurement timing designated by a trigger signal; wherein each pressure measurement apparatus in the plurality of pressure measurement apparatuses comprises: a controller configured to execute pressure measurement processing at the measurement timing designated by the trigger signal; a first input unit connected to an internal trigger generator ; a second input unit connected to an input terminal for receiving an input from an external apparatus; a trigger input switching unit configured to switch an input source of the trigger signal between the internal trigger generator and the external apparatus by selectively switching between the first input unit and the second input unit based on a control signal from the controller ; and an output unit connected to an output terminal and configured to output the trigger signal from the input source via the output terminal; a controller configured to execute pressure measurement processing at the measurement timing designated by the trigger signal; a first input unit connected to an internal trigger generator ; a second input unit connected to an input terminal for receiving an input from an external apparatus; a trigger input switching unit configured to switch an input source of the trigger signal between the internal trigger generator and the external apparatus by selectively switching between the first input unit and the second input unit based on a control signal from the controller ; and an output unit connected to an output terminal and configured to output the trigger signal from the input source via the output terminal; wherein the plurality of pressure measurement apparatuses is connected in a daisy chain such that the output terminal of a first pressure measurement apparatus in the plurality of pressure measurement apparatuses is connected to the input terminal of a second pressure measurement apparatus in the plurality of pressure measurement apparatuses , and characterized in that the output terminal of the second pressure measurement apparatus in the plurality of pressure measurement apparatuses is connected to the input terminal of a third pressure measurement apparatus in the plurality of pressure measurement apparatuses . <EOS>