Johnson Controls -- PID tuning 2

[ROCHESTER]

Hello,

I'm a MechE with 15 years of clean-room experience. I have just started a new job where I'm commissioning a suite of clean rooms. The system is a Johnson Controls(J-C)"Metasys M-5" with "DX-9100" controllers on the AHU's. I have not used J-C systems before.

The J-C controls guy will not provide the information to modify the PID gains. When asked how to change the PID parameters, he points to his head and taps.

J-C has most of the documentation on-line, but I can't find "GX-9100 Graphic Software Configuration Tool" that is referred to in the literature. The software Windows Help information is not clear to me.

Questions:

What is the basic procedure to change the DX-9100 controller's PID parameters (P and I).

If this requires a complete download of the controllers software, can this be done "on-the_fly", i.e.: with the system running?

J-C has most of the documentation on-line, but I can't find "GX-9100 Graphic Software Configuration Tool" that is referred to in the literature.

 

[MintJulep]

I don't have an answer for you.

But, it is total BS that J-C will not provide you with documentation for their product that you bought. You need to call the field guy's boss and raise some hell.

 

[imok2]

Rochester try this:

http://www.johnsoncontrols.com/contactus.htm

 

[cjeffra]

The software you need is M-Tools. The branch more likely will not sell it to you. Call JCI parts in Milwaulkee. If you know the point description, the PID loops can be adjusted from the display.

Analog Input Section
To Display Analog Inputs:
1. Press the [X] key to display analog input 1.
X1 Not Used
2. Subsequent selections of the [X] key will display the following analog inputs.

3. Press the [XT] key to display the XT’s Analog Input
XT11
4. Subsequent presses of the [X] key will display the remaining XT’s analog inputs.

To Display Analog Input Alarm Limits:
1 Press the [X] key to display the desired analog input (see "To Display Analog Inputs").
2 Press the [A] key to display the analog input low alarm limit.
3 Press the [A] key again to display the analog input high alarm limit.
4 Press the [A] key again to return to the analog input value.
To Modify Analog Input Alarm Limits:
1 Display the desired item to be modified as described above.
2 Insert the override/adjust key.
3 Press the [E] key to enter the edit mode, [K] LED will beging to blink.
4 Use the [?] or [?] keys to increase or decrease the value.
5 Press the [E] key to confirm and activate the new value, or press the [esc] key to escape from the edit mode and restore the original value. Remove the key.

Digital Input Section
To Display Digital Inputs:
1. Press the [D] key to display digital input 1.
D1 Not Used
2. Subsequent selections of the [D] key will display the following digital inputs:
D2 Not Used
D3 Not Used
D4 Not Used
D5 Not Used
D6 Not Used
D7 Not Used
D8 Not Used
3. Press the [XT] key to display the 1st XT’s Digital
D11 Not Used
4. Subsequent selections of the [D] key will display the following digital inputs:

Analog & Digital Output Section
To Display Analog & Digital Outputs:
1. Press the [Y] key to display analog output 1.
Y1 {ANALOG} Not Used Control (% Command)
2. Subsequent selections of the [Y] key will display the following:
Y2 {ANALOG} Not Used Control (% Command)
Y3 {DIGITAL} Not Used Command Enable (On = Enabled)
Y4 {DIGITAL} Not Used Command Enable (On = Enabled)
Y5 {DIGITAL} Not Used Command Enable (On = Enabled)
Y6 {DIGITAL} Not Used Command Enable (On = Enabled)
Y7 {DIGITAL} Not Used Command Enable (On = Enabled)
Y8 {DIGITAL} Not Used Command Enable (On = Enabled)
Y9 {ANALOG} Not Used Control (% Command)
Y10 {ANALOG} Not Used Control (% Command)
Y11 {ANALOG} Not Used Control (% Command)
Y12 {ANALOG} Not Used Control (% Command)
Y13 {ANALOG} Not Used Control (% Command)
Y14 {ANALOG} Not Used Control (% Command)
3. Press the [XT] key and then the [Y] key to display the next set of XT’s outputs:
Y17 {ANALOG] Not Used
4. Subsequent selections of the [Y] key will display the following:

To Override Analog or Digital Outputs:
1 Display the desired item to be overridden, as described in the previous instructions.
2 Insert the Override/Adjust Key (AS-LCP-0 Key)
3 Press the [A/M] key to enter the manual mode, [A/M] LED will blink.
4 Use the [?](Up Arrow Button) to turn item on, or the [?] Down Arrow Button to turn item Off. Control is now in manual mode.
To Release Outputs:
1 Display the desired item to be overridden, as described in the previous instructions.
2 Insert the Override/Adjust Key (AS-LCP-0 Key)
3 Press the [A/M] key to enter automatic mode, [A/M] LED will be steady, and control has been resumed to automatic.
NOTE: A flashing [A/M] LED indicates that an analog or digital output is in manual mode. A steady [A/M] LED when on a particular Analog or Digital Output indicates that the selected point is in manual mode.


Control Module Section
To Display Control Module Setpoints:
1. Press the [Z] key to display the setpoints for control module 1.
Z1 Not Used TYPE, SetPoint Value or No Setpoint Value
2. Subsequent selections of the [Z] key will display the following:

To Display Control Module Parameters:
1. Display the desired control module (see "To Display Control Module Setpoints").
2. Press the [A] key to display the process variable.
3. Subsequent selections of the [A] key will display the control module output, proportional band, reset action, rate action, standby bias, off bias and back to the control module setpoint.

Analog & Digital Constant Section
To Display Analog & Digital Constants:
1. Press the [K] key to display analog constant 1.
K1 {ANALOG} Not Used
2. Subsequent selections of the [K] key will display analog constants 2-8 and digital constants 1-32.

Digital Constants:
K1 {DIGITAL} Not Used Command (On = Enabled)


To Modify Analog or Digital Constant Setpoints or Command:
1 Display the desired item to be modified as described above.
2 Insert the override/adjust key.
3 Press the [E] key to enter the edit mode, [K] LED will begin to blink.
4 Use the [?] or [?] keys to increase or decrease the value.
5 Press the [E] key to confirm and activate the new value, or press the [esc] key to escape from the edit mode and restore the original value.
6 Remove the key.

Note: values cannot be changed if an adjust or override command from the METASYS Network is currently active.

 

[KenRad]

ROCHESTER,

Did J-C give you a documentation printout on the DX9100 program? You will need this to determine which program module is doing the PID control that you wish to modify. Then you can follow the steps above under "control module section."

The steps that cjeffra listed are correct. But there are some things to keep in mind.

* If you are used to seeing an integration term in seconds (like 50-800), the DX9100 uses an inverse of that, which they call repeats per minute, so you end up with numbers like 0.2.

* There are limitations to what you can do with this controller from the display. For example, the integration term in a PID module can only be adjusted to one decimal point. So if you wanted very slow integration, like less than 0.1, you couldn't do it from the front panel.

* There are several program module types that you can't see from the front panel at all. Fortunately, you can see the PID type.

The DX9100 controller is Johnson Controls' most versatile and powerful controller, but also the most difficult to learn. Your best bet would be to find a more cooperative technician, Johnson Controls or otherwise, and ask for help.

---KenRad

 

[ROCHESTER]

KenRad and cjeffra,

Thank you very much for the information. Sorry for the delay; I've been on vacation.

I'll use the above tomorrow when I get back to work. I'll let you know how it goes.

Thanks again,

Craig

 

[ROCHESTER]

cjeffra and KenRad,

Thanks so much for the procedure and clarifications. I was able to do the loop tuning easily.

I like the 9100's ability to be operated from the panel. The J-C M-5 networked interface is slow to update(~20 sec). The controller update is immediate and informative.

Thanks again!

Craig

 

[Ashereng]

When asked how to change the PID parameters, he points to his head and taps.

Another suggestion would be to tell J-C that on the next service call, you will not accept this technician (i.e. do not let him onto your property). Ask for another service technician.

 

[ROCHESTER]

He's an ace programmer and very good at start-up. It takes all kinds.

 

[Warpspeed]

Rochester, PID tuning is a bit of a black art but there is also an Institute of Instrumentation and Control Engineers.

These guys are the high priests of PID tuning and they publish an inexpensive do it yourself book on the fundamentals. This contains a wealth of hands on knowledge and the basic theory. There is the absolute minimum of mathematics, and it is an absolute revelation.

It discusses basic tuning parameters, how to do it, and what to look for, as well as some of the traps and unusual circumstances that can sometimes make tuning rather tricky.

In Australia contact: Institute of instrumentation and control Australia. PO Box 82, Balwyn, Victoria, 3103. Telephone 03-9816-3333, Fax 03-9857-5057

In America, Straight-Line control company (publishers) 3 Bridle Brook Lane, Newark, DE 19711-2003.

E-mail of the books author: dwstclair@aol.com

http://members.aol.com/pidcontrol/booklet.html

 

[ROCHESTER]

Warpspeed,

Thank you very much for the suggestion for the reference book. I'm always thrilled to find those gems that cut to the heart of engineering applications.

Much appreciated,

Craig

 

[Warpspeed]

Craig,

I was pretty thrilled to discover it myself a few years back. It certainly opened up a whole new world of understanding for me.

Cheers, Tony.