ModMultiSim help v3.06 - 4.4.5. Timers
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There are two basic methods for timing an interval using the ModMultiSim language:
-
Save the value of
TimeNow
in a register at the start of the interval. At the end of the interval, subtract the saved value from the current value ofTimeNow
to get the length of the interval.The register used to store
TimeNow
must be a float64 for this method to work (the value ofTimeNow
is too large to fit in any other register type). -
Increment a register by the value of
CycleTime
on each cycle during the interval.In this case, the register need not be a float64. However, if you want to use an integer register and want sub-second precision, you will have to scale
CycleTime
before adding it to the register value (e.g. multiply by 10 to work in tenths of a second).
Both these methods are illustrated in the following examples.
This timer times how long its Input is non-zero. It is called a "retentive" timer because it retains its accumulated Time when the Input becomes zero (and it has stopped timing) and continues accumulating when the Input becomes non-zero again.
In order to stop accumulating successive times, a retentive timer has to be cleared explicitly, and is done here by setting Time to 0 if Reset ($101) is non-zero.
Examples of its use might be to record how long a pump or engine has been running.
Table 21. Retentive timer
Register Address |
Register Name |
Statement |
---|---|---|
$100 | Input | |
$101 | Reset | |
$102 | Time |
if $101 != 0 then 0 else if $100 != 0 then $$ + CycleTime |
When this timer's Input turns on (becomes non-zero), it waits for a specified Delay period and then turns on its Output. When the Input turns off, the Output is turned off immediately.
Table 22. On-delay timer
Register Address |
Register Name |
Statement |
---|---|---|
$100 | Input | |
$101 | Delay | |
$102 | On time |
if $100 == 0 then TimeNow
|
$103 | Output |
if $100 == 0 then 0 else if TimeNow > $102 + $101 then 1 |
The On time register is a sampler, which records the time at which the Input turned on.
When this timer's Input turns on (becomes non-zero), it turns on its Output immediately. However, when the Input turns off, it waits for a specified Delay period before turning off its Output.
Table 23. Off-delay timer
Register Address |
Register Name |
Statement |
---|---|---|
$100 | Input | |
$101 | Delay | |
$102 | Off time |
if $100 != 0 then TimeNow
|
$103 | Output |
if $100 != 0 then 1 else if TimeNow > $102 + $101 then 0 |
This timer combines the on-delay timer and off-delay timer.
Table 24. On/off-delay timer
Register Address | Register Name | Statement |
---|---|---|
$100 | Input | |
$101 | On delay | |
$102 | Off delay | |
$103 | On time |
if $100 == 0 then TimeNow
|
$104 | Off time |
if $100 != 0 then TimeNow
|
$105 | Output |
if $100 != 0 && TimeNow > $103 + $101 then 1 else if $100 == 0 && TimeNow > $104 + $102 then 0 |
This timer repeatedly waits for a set Period and then sets its Output to 1 for one cycle.
Table 25. Periodic timer
Register Address | Register Name | Statement |
---|---|---|
$100 | Period | |
$101 | Output |
if $$ != 0 then 0 else if $102 >= $100 then 1 |
$102 | Elapsed time |
if $$ >= $100 then ($$ - $100) + CycleTime else $$ + CycleTime |
The Elapsed time register holds the
time since the start of the current timer period.
It is incremented by
CycleTime
on each cycle until it equals or exceeds the
Period, when it is re-initialized before
being incremented.
The timer cycle and ModMultiSim's cycle are not synchronized, so the
Elapsed time has to be re-initialized to
the partial ModMultiSim cycle ($$ - $100
) that has already
occurred instead of to zero.