Cirrus Logic CobraNet - Manual (Page 31)

CobraNet Programmer’s Reference
Management Interface Variable Reference
DS651PM25
©
Copyright 2006 Cirrus Logic, Inc. 31
be used to extend the useful range of the timer. Both may be safely ignored for most
applications.
SNMP: TimeTicks is reported as a 32-bit integer in units of 100ths of a second. For
example, a reported value of
1000 indicates a 10-second timer reading. As seen through
SNMP,
TimeTicks variables roll over after 2 32
100ths of a second (42,949,672.96 seconds
- over one year).
6.2.6 Counter
Counters are never writable and cannot be reset. They indicate the count value since the
interface was last restarted (
sysUpTime = 0). Counters roll over to zero after reaching
their maximum value of 2
24
(16,777,216) on 24-bit platforms and 2
32
(4,294,967,296) on
32-bit platforms.
24-bit HMI: Counter value is represented as a single 24-bit word.
32-bit HMI: Counter value is represented as a single 32-bit word.
6.2.7 Counter2
Counter2 is specific to 24-bit platforms and is a 48-bit unsigned event counter. Counter2
rolls over after 2
48
counts. Counters are never writable. On 32-bit platforms
Counter2 is
identical to the Counter type.
24-bit HMI: The counter value is stored in two successive memory locations. The most-
significant word appears first. It is suggested that one read the MS word followed by LS
word followed by a second read of the MS word and verify that the MS word has not
changed during the LS read (if so, start over).
32-bit HMI: Counter value is represented in the same single 32-bit word used for the
Counter type.
SNMP: Only the least-significant 32-bits of the counter value are reported. The counter
appears to wrap at 2
32
and conforms to the expected behavior for the standard SNMP
Counter data type.
6.2.8 Integer
A single-precision, signed integer. Valid range is -2
23
(-8,388,608) to 2
23
-1 (8,388,607) on
24-bit platforms and -2
31
(-2,147,483,648) to 2
31
-1 (2,147,483,647) on 32-bit platforms.
HMI: Signed data is represented in a single word in 2's complement form.
SNMP: On 24-bit platforms, Bad Value error may be reported if the value magnitude
exceeds the 24-bit signed integer range on a set operation.
Table 15. TimeTicks Layout, 32-bit Platforms
MS MH ML LS
Word 1 Rollover MS Rollover LS Timer MS Timer MH
Word 2 Timer ML Timer LS Fractional LS Fractional MS