A combination of a graphical user interface (114; 156; 200; 400; 500) and a controller (112; 134; 158), the graphical user interface (114; 156; 200; 400; 500) comprising: a first graphical interface (202; 402; 502) representing a first welding parameter; and a second graphical interface (204; 504) representing a second welding parameter, each graphical interface being controlled by the controller; the combination being characterised in that the controller (112; 134; 158) is configured to: receive data corresponding to output values for each of the first and second welding parameters, respectively; display a first marker (206; 406; 506) on the first graphical interface representing the output value associated with the first welding parameter; display a second marker (218; 508) on the second graphical interface representing the output value associated with the second welding parameter; determine a range of values for each of the first and second welding parameter based on the output value associated with the second welding parameter and one or more corresponding welding process parameters; generate a first graphical band (210; 410; 510) representing the range of values for the first welding parameter; generate a second graphical band (224, 225; 524) representing the range of values for the second welding parameter; display the first and second graphical bands on the first and second graphical interfaces, respectively adjust a position of the first graphical band (210; 410; 510) on the first graphical interface (202; 402; 502) based on a change in the output value associated with the second welding parameter. a first graphical interface (202; 402; 502) representing a first welding parameter; and a second graphical interface (204; 504) representing a second welding parameter, each graphical interface being controlled by the controller; the combination being characterised in that the controller (112; 134; 158) is configured to: receive data corresponding to output values for each of the first and second welding parameters, respectively; display a first marker (206; 406; 506) on the first graphical interface representing the output value associated with the first welding parameter; display a second marker (218; 508) on the second graphical interface representing the output value associated with the second welding parameter; determine a range of values for each of the first and second welding parameter based on the output value associated with the second welding parameter and one or more corresponding welding process parameters; generate a first graphical band (210; 410; 510) representing the range of values for the first welding parameter; generate a second graphical band (224, 225; 524) representing the range of values for the second welding parameter; display the first and second graphical bands on the first and second graphical interfaces, respectively adjust a position of the first graphical band (210; 410; 510) on the first graphical interface (202; 402; 502) based on a change in the output value associated with the second welding parameter. receive data corresponding to output values for each of the first and second welding parameters, respectively; display a first marker (206; 406; 506) on the first graphical interface representing the output value associated with the first welding parameter; display a second marker (218; 508) on the second graphical interface representing the output value associated with the second welding parameter; determine a range of values for each of the first and second welding parameter based on the output value associated with the second welding parameter and one or more corresponding welding process parameters; generate a first graphical band (210; 410; 510) representing the range of values for the first welding parameter; generate a second graphical band (224, 225; 524) representing the range of values for the second welding parameter; display the first and second graphical bands on the first and second graphical interfaces, respectively adjust a position of the first graphical band (210; 410; 510) on the first graphical interface (202; 402; 502) based on a change in the output value associated with the second welding parameter.