Saw signal generator
Block name
B4_SAW_GENERATOR
ST call
PROGRAM B4_TEST VAR O1,O2: REAL; FB: LIB.CORE.V1_1.B4_SAW_GENERATOR:= (MINIMUM:= 0, MAXIMUM:= 10); END_VAR FB(OUT => O1, TRES => O2); END_PROGRAM
Library
LIB\CORE
Version
V1.1
Description
The block is a saw signal generator with minimum and maximum value setting, minimum and maximum value time duration setting, and ramp time setting. Another output provides remaining time until the end of the period.
Version V1.1
Correction of a combination of short cycles and long periods (eg cycle 1 ms and period 60 s). The generator did not hold time base and generated incorrect timing.
Inputs
| Input | Type | Description | Default value |
| ENABLE | BOOL | Enable of functionality of the block | True |
| TMIN | TIME | Time interval for OUT=MINIMUM. | 0s |
| TRAMP | TIME | Time interval for the OUT to rise from MINIMUM to MAXIMUM. | 1s |
| TMAX | TIME | Time interval for OUT=MAXIMUM. | 0s |
| MINIMUM | REAL | Minimum value of the output signal. | 0 |
| MAXIMUM | REAL | Maximum value of the output signal. | 1 |
| PAUSING | BOOL | Behaviour when paused | True |
Outputs
| Output | Type | Description |
| OUT | REAL | Output saw signal. |
| TRES | TIME | Remaining time until the end of the period. |
Function
The output signal OUT provides a saw signal with intervals Tmin, Tramp, and Tmax and limit values of MINIMUM and MAXIMUM. The block contains another output signal, Tres, which is remaining time until the end of the current period T, see image below. The block also contains a boolean input ENABLE which switches the generator off (when ENABLE: = false). The block behaviour after switching off depends on the PAUSING parameter (see image below):
- PAUSING=FALSE and ENABLE=FALSE: OUT is set to MINIMUM + MAXIMUM / 2. As soon as ENABLE goes to TRUE, the period time starts from the beginning.
- PAUSING=TRUE and ENABLE=FALSE: OUT is frozen. As soon as ENABLE goes to TRUE, the sequence continues from the previous value.
Application example
Function B4 generates a saw signal on the O1 output, with period of 1 second, minimum value of 0, and maximum value of 1.