User Manual

64 Reader Data Interface PLUS System Manual
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In this example, the Reader replied with the following statistics: 1000 packets received correctly, 5
packets received with incorrect CRC, 2 false detections, no FIFO overflows, 10 packets received
that produced bad TOA calculations, an uptime of 1000000 seconds, a temperature of 30.5 degC,
the PLL was never unlocked, and no sync marker errors have occurred. Internally, the Reader
keeps all statistics in unsigned 32-bit integers. The statistics counters will wrap around to zero and
continue incrementing if they overflow.
The alarm commands and their responses are discussed in the following section.
3.4.3 Reader Alarms
As described previously, the TOA packet includes a bit that is used to indicate Reader alarms. An
alarm is any error condition in the Reader that may require corrective action. Internally, the Reader
maintains both a status word that shows what alarms, if any, have been generated, and an enable word
which enables/disables the Reader’s setting the alarm bit in the TOA packet.
The alarm status word is a 32-bit word, each bit of which corresponds to an alarm source. See Figure
3-5: Alarm Status and Alarm Enable Word Bit Position Definition for the bit definition of the alarm
sources. It always shows the current status of an alarm source, even if the alarm source has been
disabled via the alarm enable word described below. A ―1‖ in a bit position indicates that an alarm has
been generated for the corresponding alarm source; a ―0‖ indicates no alarm exists for the
corresponding alarm source. The alarm status word is read using the SENDALARMSTATUS
command. Once an alarm source causes its alarm bit in the TOA packet to be set, the bit will remain
set until the alarm source is cleared using the CLEARALARM command. This command takes a
single parameter, which is the bit mask of the alarm sources to clear.
The alarm enable word is also a 32-bit word, and has the same alarm source bit definitions as the alarm
status word. In the alarm enable word, a ―1‖ in a bit position indicates that the corresponding alarm
source is enabled, and, if an alarm on that source occurs, the alarm bit in the TOA packet will be set. A
―0‖ in a bit position in the alarm enable word means that the alarm source is disabled – even if an alarm
condition occurs on that source, the Reader will not set the alarm bit in the TOA packet . The alarm
enable word can be read and written using the SENDALARMENABLE and SETALARMENABLE
commands.
At startup, the Reader sets the alarm enable word to the value that was last set by the
SETALARMENABLE command. If the alarm enable word has never been set using this command,
the alarm enable word is set to 0xFFFFFFFF (all alarms are enabled). Every time the Reader sends a
TOA packet, the alarm bit is set if an alarm source is set in both the alarm status word and the alarm
enable word.