View source for RxUsbQueryNumberDevices

==Description==
Obtains the Total Number of currenly attached USB devices. 

==Syntax==
<pre>
rc = RxUsbQueryNumberDevices(Number)
</pre>

==Parameters==
; Number : receives the Total Number. 

==Return Code==
<pre>
0x0000 - NO_ERROR
</pre>
===Errors===
<pre>
0x0057 - ERROR_INVALID_PARAMETER
0x1B58 - USB_NOT_INIT
0xFF13 - ERROR_I24_INVALID_PARAMETER
0xFF1F - ERROR_GEN_FAILURE
0xFF57 - ERROR_INVALID_PARAMETER
</pre>
==Remarks==

==Example Code==
<pre>
/* add RxUsbQueryNumberDevices */
rc = RxFuncAdd('RxUsbQueryNumberDevices','usbcalls','RxUsbQueryNumberDevices')
say '+RxUsbQueryNumberDevices(),RC=0x'd2x(rc)

/* invoke RxUsbQueryNumberDevices */
drop Number /* receives number of devices */
rc = RxUsbQueryNumberDevices(Number)
say '*RxUsbQueryNumberDevices(),RC=0x'd2x(rc)

/* drop RxUsbQueryNumberDevices */
rc = RxFuncDrop('RxUsbQueryNumberDevices')
say '-RxUsbQueryNumberDevices(),RC=0x'd2x(rc)
</pre>

==Related Functions==
* [[RxUsbQueryDeviceReport]]
* [[RxUsbQueryDeviceInfo]]
* [[RxUsbOpen]]

[[Category:USBCalls]]