How to switch devices on and off

Controlling electrical/electronic equipment from a PC or Laptop allows those devices to be operated remotely, automatically, and from a master distribution point. This is a key requirement for computer automation. The Digital I/O Module, Digital Output Module, and Solid-State Relay Module can be used to switch external devices on and off, and to gain control of their user-operated buttons and switches which would normally require direct physical interaction. Refer to the product data sheets to determine which of these DAQ Modules is best for your application.

To control an external device from a PC, ModCom provides a couple of Screen Objects that are ideal for this task. A Push Button or Button Array can be placed on the screen and used to send commands to a DAQ Module with a simple mouse click. Simply choose one of these objects from the <Place Object> menu at the top of the screen and move it to the desired position using the mouse. Follow the steps below to set up the object for operation.

Using a Push Button:

Step 1: To set the properties of the Push Button, right-click on the object. This will bring up the Properties dialog box which contains a number of user defined attributes which can be used to customize the Push Button's appearance and operation.

Step 2: From the command set shown in Table 2 of the product data sheet, choose the command string which is required to turn on the device connected to the DAQ Module and type it in the box at the upper right hand corner of the Press-Button Function section.

Step 3: From the command set shown in Table 2 of the product data sheet, choose the command string which is required to turn off the device connected to the DAQ Module and type it in the box at the upper right hand corner of the Release-Button Function section.

Step 4: Close out the dialog box and start the main run-time loop by clicking on the green "Run" button at the top of the screen. Once in run mode, you can use the left mouse button to press and hold down the Push Button and ModCom will transmit the turn-on command which you entered in the dialog box. Once releasing the Push Button, ModCom will transmit the turn-off command which you entered in the dialog box.

Of course it is permissible to use two separate Push Buttons to turn on and off a device. One to turn it on, another to turn it off. To do this, simply place two Push Buttons on the screen and configure each to transmit the required commands when they are pressed down. A Push Button does not have to use both its "press" and "release" functions in order to operate correctly. To disable one of the functions, leave the command string box blank.

Using a Button Array:

Step 1: To set the properties of the Button Array, right-click on the object. This will bring up the Properties dialog box which contains a number of user defined attributes which can be used to customize the Button Array's appearance and operation.

Step 2: Check the box "Execute if selection is changed" to have the Button Array automatically execute its function each time the user changes the active button during run-time. Also select button "C" in the "Button List" and click on "Delete Button" and then do the same with button "D". This will remove these two buttons since only buttons "A" and "B" will be used in this application.

Step 3: Select button "A" and click on "Edit Button". From the command set shown in Table 2 of the product data sheet, choose the command string which is required to turn on the device connected to the DAQ Module and type it in the box next to the "Transmit Command" function and then click on "OK".

Step 4: Select button "B" and click on "Edit Button". From the command set shown in Table 2 of the product data sheet, choose the command string which is required to turn off the device connected to the DAQ Module and type it in the box next to the "Transmit Command" function and then click on "OK".

Step 5: Close out the dialog box and start the main run-time loop by clicking on the green "Run" button at the top of the screen. Once in run mode, you can use the left mouse button to click on button "A" and ModCom will transmit the turn-on command which you entered in the dialog box. Clicking on button "B" will transmit the turn-off command which you entered in the dialog box.