UAP0026 - USC Application

This application is a backup PID controller and operates in two modes of operation.

Auto Mode

1. The ACCESS module displays pressure measured byCH1 in auto mode.
2. The mA signal going to valve 1 is measured (CH2) and retransmitted to value 2 with an offset value added.
3. The second input measures a pressure; if the pressure goes above a set point a backup PID function will further reduce the output valve angle to control output.

Manual Mode

1. The ACCESS module displays 'Valve2' angle as a percentage in manual mode.
2. 'Valve2' angle can be adjusted using AM702 hot keys.

Operation

1. To enter manual mode press "BACK" + "NEXT" simultaneously buttons. The mA output will be displayed as a percentage of "Valve 2" and relay 1 will also switch on to indicate manual mode.
2. Press "UP" the output will increase by 4% per second until the "BACK" button is pressed.
3. Press "UP" + "BACK" the output will increase by 20% per second until the "BACK" button is pressed.
4. Press "DOWN" the output will decrease by 4% per second until the "BACK" button is pressed.
5. Press "DOWN" + "BACK" the output will decrease by 20% per second until the "BACK" button is pressed.
6. To enter auto mode press "UP" + "NEXT". The pressure measured by CH1 will be displayed and relay 1 will switch off to indicate auto mode.

The Standard Program Details

Declarations

Variable	Label	Description	Value
CH1	kPa PT	kPa measurement input	0 to 5000
CH2	Valve 1	Valve 1 setting from PID 1	0 to 100%
Con_a	PB %	Proportional band setting	(40)
Con_b	I time S	Integration setting	??
Con_c	D time S	Differential setting	??
Con_d	EquTime	Set to same value as the equation evaluation timer.	(0.1)
Con_e	PID SP	PiD controller setpoint	2900
Con_f	IntReset	Integration reset value	(1200)
Con_f	Offset %	Value added to reading on input 2	2
Con_g	Val 50	equation constant	50
Con_i	Val 2	equation constant	2
Con_j	Val 100	equation constant	100
Mem4	Valve 2	Valve output	0 to 100 %
Mem6	i	Integral error signal	0-5000
Mem7	PiD	Controller output error signal	0-5000
Mem8	delta	Difference between set point and process feedback (error)
Mem9	old delta	value of delta in previous sample.
Timer enable:	Y
Timer sec:	0.1
Update on input:	N

The command Gosub PID referred to in the program list is documented in UAP0025. Please refer to UAP0025 for instructions on set-up and equation sampling time.

Program List

Program List	Comment
If HK0011-Manual	Goto Manual if hot keys for manual mode are pressed
If HK1001-Auto	Goto Auto if hot keys for auto mode are pressed
Read Var00	Read flag to determine if in auto or manual mode
If<0 Goto Manual	If Var00 is less than 0 manual mode is running goto Manual.
Del S	Program will only get to this point if in auto mode. Clear stack.
Gosub PID	Calculate PID correction signal using standard PID algorithm please refer to UAP0025 for more details.
Read Mem7	Load PID correction signal into stack.
Con_h	Read 50
Divide	Convert PID correction from 5000 error signal to a 100 error signal
Read Ch2	Get reading from input 2 (Valve 1 setting)
Con_g	Read offset value
Add	Add offset to valve 1 setting
min	Get the smallest value out of (Valve 1 + offset) and (PID error)
Save Mem4	Save result to go to output.
Send M4
Exit	----------------------------------------------
LAB: Auto	Initialize flag for auto mode switch off relay and clear last pressed hot key code.
Display Ch1
RY1 off
Con_i
Save Var00
HotK off
Exit	-----------------------------------------------------------
LAB: Manual	Initialize flag for Manual mode and switch on relay
Display Mem4
RY1 on
Con_i
CngSgn
Save Var00
Del S
Read Mem4	Read current setting of output.
If HK0001-StopRamp	If next button is pressed then go to Stop ramp
If HK1000-RmpUpS	If up button is pressed then go to ramp up slow
If HK1010-RmpUpF	If up + back pressed then go to ramp up fast
If HK0100-RmpDowS	If down pressed then go to ramp down slow
If HK0110-RmpDowF	If down + back pressed then go to ramp down fast
Exit	--------------------------------------------------------------
LAB: StopRamp	To stop ramping clear the last pressed key code.
HotK off
Exit	-------------------------------------------------------------
LAB: RmpUpS	Ramp up slowly by adding 0.2 to memory 4 every 100ms.
Con_d	Read 0.1
Con_i	Read 2
Multiply	2 x 0.1 = 0.2
Add	Add 0.2 to value in stack (memory 4)
Goto ChkLimit	Go to Check limits then save
Exit	-----------------------------------------------------------
LAB: RmpUpF	Ramp up fast by adding 2 to memory 4 every 100ms.
Con_i	Read 2
Add	Add 2 to value in stack (memory 4)
Goto ChkLimit	Go to Check limits then save
Exit	-----------------------------------------------------------
LAB: RmpDowS	Ramp down slowly by subtracting 0.2 from memory 4 every 100ms.
Con_i
Con_d
Multiply
Subtract
Goto ChkLimit
Exit	-----------------------------------------------------------
LAB: RmpDowF	Ramp down fast by subtracting 2 from memory 4 every 100ms.
Con_i
Subtract
Goto ChkLimit
Exit	-----------------------------------------------------------
LAB: ChkLimit	Check that the value in stack is between 0 and 100
Save Mem4	Save value in stack
If<0 Goto SetTo 0
Con_j
Subtract
If>0 Goto SetTo100
Exit	-----------------------------------------------------------
LAB: SetTo 0
Read Var21
Save Mem4
Exit
LAB: SetTo100	-----------------------------------------------------------
Con_j
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.
UAP00261.usc	Initial release works with USC Config 104 and older usc modules but contains no auto manual operating mode and a older PID algerithim
UAP00262.usc	Will only work with USC Config 106 and USC modules containing S/W 1.06.02 or higher It has auto and manual operating modes using hotkeys and a newer PID algarithim.
UAP0026r.usc	Contains the same auto manual feature as issue 2 however the PID function was written by Rick Joubert of Epic Energy for a specific application. Will only work with USC Config 106 and USC modules containing S/W 1.06.02 or higher