How to control many USB kits from your own application (for example, controlling 12 stepper motors by 4 USB Stepper Motor Controllers)

Transcription

1 How to control many USB kits from your own application (for example, controlling 12 stepper motors by 4 USB Stepper Motor Controllers) Each USB Stepper Motor Controller will allow you to control three bi-polar stepper motors. To control uni-polar stepper motors, it is necessary to use more digital lines and automatically you will have one to two uni-polar steppers controlled by one Controller. You can use the remaining lines if you require to drive relays or control end switches. This note will show you the concept of connecting more Softmark USB kits and controlling them from one application. The USB kits can also interact with other USB kits, for instance, the 4 Channel Voltmeter. Voltage read by the USB 4 Channel Voltmeter can be displayed by the USB LCD Module Interface and if voltage is at a certain level, you can set the relay on the USB Relay Card, depending on your application. Figure 1 below shows how four USB Stepper Motor Controllers are connected. Remember, the maximum number of devices connected to the USB bus cannot exceed 127. USB Bus USB HUB Computer Controller USB Controller D USB Controller A USB Controller B USB Controller C The next 3 USB Controllers can control another 9 stepper motors. Note that all Controllers can be controlled from the same application, from one USB bus. One Controller can control 3 stepper motors +12V from the power supply Softmark: Controlling many USB kits from your own application 1

2 Figure 1. Four USB Stepper Motor Controllers (with a maximum of 12 stepper motors) controlled by one application. Application software The generic USB.OCX can detect the USB device and can transfer data to it. However, if you need to control more USB Controllers (for example, USB Stepper Motor Controllers) from just one application, you will need to install more USB.OCXs and each one will control one particular USB Controller. Each software on a Controller s PCB can talk to just one USB.OCX. In general, Controllers will have indexes like B, C, or D and accordingly, you will need specific OCXs (such as USB_B.OCX, USB_C.OCX, or USB_D.OCX) in order to separately control each USB Controller from your application. Softmark can supply Controllers with the above indexes, for example, B and an OCX for that, namely USB_B.OCX. This setup is optional so please softmark@ar.com.au for details. Figure 2 below shows four Stepper Motor Controllers controlled from the one application. The front panel shows you four OCXs, one for each Controller. The included sample program will explain how the additional Stepper Motor Controllers can be controlled from the one program. Note that up to 12 stepper motors can be controlled from one program. USB.OCX (main one) USB_D.OCX to control Controller D USB_B.OCX to control Controller B USB_C.OCX to control Controller C Figure 2. Front panel of sample application controlling 12 stepper motors. Softmark: Controlling many USB kits from your own application 2

3 How software controls separate USB Stepper Motor Controllers A few lines of code will guide you here. USB.WrP0 (255) REM Set all lines on Port P0 (main controller) to logic 1(high) USB_B.WrP0 (255) REM Set all lines on Port P0 (B-controller) to logic 1(high) USB_C.WrP0 (255) REM Set all lines on Port P0 (C-controller) to logic 1(high) USB_D.WrP0 (255) REM Set all lines on Port P0 (D-controller) to logic 1(high) Imagine you have four USB.OCXs and each one controls a particular USB Stepper Motor Controller. To control the first Stepper Motor Controller, you will use USB.OCX. To control the fourth Controller, you have to write a code using USB_D.OCX, and so on. This shows you how to control four USB Stepper Motor Controllers. You can use two or three of them and the approach will be the same. You can control other devices by using USB buses that are not connected in your USB hub. If you want to control four different Softmark USB kits, the approach will again be the same. This setup is more powerful and will allow you to control USB kits such as the Relay Card by other USB kits, such as the 4 Channel Voltmeter, if, for instance, voltage/temperature drops to a certain level. This status can be displayed on another USB kit, the USB LCD Module, and can, for example, activate a relay on the Relay Card. There are endless possibilities, limited only by imagination. Softmark: Controlling many USB kits from your own application 3

4 USB Bus Computer Controller USB HUB USB Controller D USB Thermometer/ Thermostat USB Relay Card USB 4 Channel Voltmeter Figure 3. Various connected USB kits can interact with each other. Softmark: Controlling many USB kits from your own application 4

5 Another example of kits controlled by the same application Figure 4. USB 4 Channel Voltmeter reads input voltages and the values are shown on the USB LCD Module (Note that the USB LCD Module already has a separate USB_LCD.OCX that is included in the kit). Note: Additional USB.OCXs for Softmark s kits are optional and can be supplied separately. USB.OCXs come with a sample application program (source code is included), which helps you to understand how data is transferred between your application and a particular Softmark USB device. Copyright 2004 Softmark All rights reserved. The information presented in this document is believed to be accurate and reliable and may be changed without notice. No liability will be accepted for any consequences of its use. Softmark: Controlling many USB kits from your own application 5