State Logic; Suction Protector plus Oil Seal Monitor
UAP0012 - USC Application
|
 This
example is used in a pumping station to monitor a water pump.
It uses fail safe logic (relay closed when good)
and is part of an overall control system.]
Operating Description and State Diagram
CH2 is a standard resistance alarm.
CH1 uses values stored in MEM4 and MEM5 to perform both timing and state
control functions as outlined in the following table.
Note that the relay must switch on at power on and inhibit only prevents
the current alarm and timer from operating if the RY1 has not already
latched off. If RY1 has latched off only reset can restart the system
(close RY1).
x = don't care, Hi = ON, Low = Off.
| Event |
Inhibit
P2 |
Reset P1 |
Current
Alarm |
RY1 |
Mem4 |
Mem5 |
| Power on |
x |
x |
x |
Off |
x |
0 |
| After Power on |
Hi |
Low |
Disabled |
On |
Max Time |
-1 |
| Motor Starts |
Low |
Low |
Enabled with time delay |
On |
Max Time |
1 |
| Motor current low for short time |
Low |
|
Enabled with time delay |
|
count down |
1 |
| Motor current OK |
Low |
Low |
Enabled with time delay |
Off |
Max Time |
1 |
| Motor current low no suction |
Low |
Low |
Under current and time out |
Off |
-1 |
1 |
| Motor stops |
Hi |
Low |
Disabled |
Off |
-1 |
1 |
| Reset |
Hi |
Hi |
Disabled |
On |
|
0 |
| Same as after power on |
|
|
|
|
|
-1 |
Declarations
| USC Component |
Eng. Unit / Label |
Description |
| CH1 |
Amps |
250m Vac = 5 Aac |
| CH2 |
Oil Seal |
Resistance measurement |
| M4 |
Timer |
Timer counter |
| M5 |
PwOnRest |
Power on / Reset latch |
| P1 |
|
Reset |
| P2 |
|
Inhibit |
| Timer enable |
|
Y |
| Timer sec: |
|
0.5 |
| Con_a |
Ch1Low A |
Setpoint (3) |
| Con_b |
Inc/Flag |
Timer increment + fail (-1) |
| Con_c |
Time0.5S |
Time out time x Timer sec If Con_c = 10 and Timer =
0.5 then 10x0.5 = 5 Sec. |
| Con_j |
zero |
Zero (0) |
Program List
| Command |
Comment |
| Send M4 |
Send timer value for debug purposes |
| Send M5 |
Send power on reset latch for debug |
| Gosub ChkReset |
Check for Reset |
| Gosub ChkPowOn |
Check Before Power On |
| Read Mem4 |
Check for Latch Fail |
| If < 0 Goto LatchOff |
|
| If P2 Goto Inhibit |
Inhibit |
| Del S |
|
| Read Ch1 |
Check for under current |
| Con_a |
|
| Subtract |
|
| If < 0 Goto StpTimer |
Go to timer if under current |
| Con_c |
Reset timer |
| Save Mem4 |
|
| Exit |
--------------------- |
| Line StpTimer |
Run timer |
| Del S |
|
| Read Mem4 |
|
| Con_b |
|
| Add |
decrement timer |
| Save Mem4 |
|
| If < 0 Goto LatchOff |
Check for time out |
| Exit |
--------------------- |
| Line LatchOff |
Latch relay off |
| RY1 off |
|
| Con_b |
|
| Save Mem4 |
|
| Exit |
--------------------- |
| Line ChkPowOn |
Check for before power on |
| Read Mem5 |
|
| If = 0 Goto LdPowOnS |
|
| Del S |
|
| Return |
|
| Exit |
--------------------- |
| Line LdPowOnS |
Load power on state |
| Del s |
|
| RY1 on |
|
| Con_c |
|
| Save Mem4 |
|
| Con_b |
|
| Save Mem5 |
|
| Del S |
|
| Del S |
|
| Return |
|
| Exit |
--------------------- |
| Line ChkReset |
Check for reset |
| If P1 Goto Reset |
|
| Return |
|
| Exit |
--------------------- |
| Line Reset |
Reset from latched state |
| Con_j |
|
| Save Mem5 |
|
| Del S |
|
| Return |
|
| Exit |
--------------------- |
| Line Inhibit |
Inhibit |
| Con_c |
|
| Save Mem4 |
|
| Exit |
--------------------- |
| < end > |
|
USC Programs
| File |
Comment |
Help |
If unexpected results occur when loading the .usc file press back
and click on help for instructions. |
UAP00121.usc |
First Issue. |
|
UAP00122.usc |
Convert to USC config 105 standard. |
|
Analogue Process Control Services - The Signal Conditioning Specialist