Omron SYSMAC C20K Operation Manual page 115

Timer and Counter Instructions
Dedicated Bits
Upper and Lower Limit
Setting
Lower limit
DM 00
DM 02
DM 04
DM 06
DM 08
DM 10
DM 12
DM 14
DM 16
DM 18
DM 20
DM 22
DM 24
DM 26
DM 28
DM 30
104
The transferred count value is then compared with the upper and lower limits
of a set of ranges which have been preset in DM 00 through DM 31. If the
current value is within any of the preset ranges, the corresponding bit of the
results word, R, is turned ON. The bit in the result word will remain ON until
the current value is no longer within the specified range.
When the reset input (1804) goes ON, the present value is cleared to 0000,
even if the start input is OFF, and all bits in R are set.
Note RDM(60) cannot be used to create a high-speed counter. If you require a
high-speed counter, use HDM(61).
When using the counter, the following bits are reserved and cannot be used
for any other purpose:
SR bit 1804 (reset input)
SR bit 1805 (count input)
SR bit 1806 (UP/DOWN selection input)
TC 46 (present count value)
DM 00 to 31 (upper and lower limits)
Note If a power failure occurs, the count value of the counter immediately before
the power failure is retained.
The following table shows the upper and lower limits that need to be set in
DM 00 through DM 31. In this table, S is the present value of counter 46 and
R is the result word.
Upper limit Present value of the counter
DM 01
Value of DM 00
DM 03
Value of DM 02
DM 05
Value of DM 04
DM 07
Value of DM 06
DM 09
Value of DM 08
DM 11
Value of DM 10
DM 13
Value of DM 12
DM 15
Value of DM 14
DM 17
Value of DM 16
DM 19
Value of DM 18
DM 21
Value of DM 20
DM 23
Value of DM 22
DM 25
Value of DM 24
DM 27
Value of DM 26
DM 29
Value of DM 28
DM 31
Value of DM 30
00
S value of DM 01
01
S value of DM 03
02
S value of DM 05
03
S value of DM 07
04
S value of DM 09
05
S value of DM 11
06
S value of DM 13
07
S value of DM 15
08
S value of DM 17
09
S value of DM 19
10
S value of DM 21
11
S value of DM 23
12
S value of DM 25
13
S value of DM 27
14
S value of DM 29
15
S value of DM 31
Section 5-11
Bit of R that
turns ON