Tyco Electronics LD9000 Series User Manual
Page 92
Section 4. USB Communications
17
SERIAL_NUM PROPERTY
Property ID:
1
Property Type:
String
Length:
0 – 15 bytes
Get Property:
Yes
Set Property:
Yes
Default Value:
The default value is no string with a length of zero.
Description:
The value is an ASCII string that represents the device’s serial number. This
string can be 0 – 15 bytes long. This property is stored in non-volatile
EEPROM memory so it will not change when the unit is power cycled. The
value of this property, if any, will be sent to the host when the host requests
the USB string descriptor. When this property is changed, the unit must be
power cycled to have these changes take effect for the USB descriptor. If a
value other than the default value is desired, it can be set by the factory upon
request. Examples follow.
Example Set SERIAL_NUM property Request (Hex):
Cmd Num
Data Len
Prp ID
Prp Value
01 04
01
31
32
33
Example Set SERIAL_NUM property Response (Hex):
Result Code Data Len
Data
00 00
Example Get SERIAL_NUM property Request (Hex):
Cmd Num
Data Len
Prp ID
00 01
01
Example Get SERIAL_NUM property Response (Hex):
Result Code Data Len
Prp Value
00
03
31 32 33
POLLING_INTERVAL PROPERTY
Property ID:
2
Property Type:
Byte
Length: 1
byte
Get Property:
Yes
Set Property:
Yes
Default Value:
10
Description:
The value is a byte that represents the devices polling interval for the Interrupt
In Endpoint. The value can be set in the range of 1 – 255 and has units of
milliseconds. The polling interval tells the host how often to poll the device
for card data packets. For example, if the polling interval is set to 10, the host
will poll the device for card data packets every 10ms. This property can be
used to speed up or slow down the time it takes to send card data to the host.
The trade-off is that speeding up the card data transfer rate increases the USB
bus bandwidth used by the device, and slowing down the card data transfer