Application Specific Controllers Technical Manual 636.3 VMA Controller Section Technical Bulletin Issue Date 0199 VMA Demo Unit Introduction This document provides information on how to set up and operate the VMA Demo Unit. Figure 1: VMA Demo Unit New software technologies used in the VAV Modular Assembly (VMA) lead to some very powerful Variable Air Volume (VAV) control techniques. P-Adaptive is a Johnson Controls patented control loop technology that provides quick and accurate VAV damper operation. P-Adaptive can be best understood by a simple demonstration of VMA response. An operating VMA and VAV damper are used to demonstrate the flow loop reaction to large changes in flow setpoint. The demo unit parameters, displayed using the data graphing feature in HVAC PRO for Windows, dramatically exhibit the flow loop reaction and changes. Such changes result from switching operation modes (i.e., Standby to Occupied) or by large demand changes (i.e., empty to full conference room). 1999 Johnson Controls, Inc. 1 Part No. 24-8967-7, Rev. www.johnsoncontrols.com Code No. LIT-6363094
Equipment Setup The following equipment is required to set up the VMA Demo Unit: Demo Unit, AP-VMADEMO-0 (includes fan, VAV damper, VMA, transformer, and two magnahelic gauges) Computer with Microsoft Windows HVAC PRO for Windows Version 7.00 or later MM-CVT101-0 (RS-232/RS-485 converter) To set up the VMA Demo Unit: 1. Connect the transformer s 24 VAC screw terminal connector to Terminals 1 and 2 of the VMA. Plug the VMA Demo Unit fan (switch off) and the VMA transformer into 120 VAC line voltage. Note: On power up, the VMA runs the damper actuator to both end stops to automatically set damper travel. The VMA uses a stepper motor actuator, which counts the incremental steps to a damper end stop. The damper travel required (45, 60, 90 ) is determined when configuring the VMA. 2. Connect a Personal Computer (PC) laptop with HVAC PRO for Windows, Version 7.00 or later to the VMA via the 8-pin phone jack connection. 3. Using HVACPRO for Windows, select Action > Controller Information. Click on Single Device, then click OK. On the next screen, select the correct communications port and the N2 Bus type. Input the correct N2 address to match the VMA DIP switch settings. Click OK. Note: The next window lists all current parameters. If the animated jogger is running at the bottom of the screen, the communications between the VMA and the computer is working. If it indicates communications is not working, check the PC-to-CVT connections and N2 addresses and try again. 4. Click Exit. 5. If the correct demo configuration file (demo.cfg) already exists, but is not loaded into the unit, select File > Open in HVACPRO for Windows and select the correct demo.cfg file. Skip to Step 10. If the correct demo configuration file (demo.cfg) is already loaded into the demo unit, skip to the Demonstration section of this document. Otherwise, proceed to Step 6. 6. Select File > New in HVACPRO for Windows to build a demo configuration for the VMA. Select the following: Application Group: VAV Applications Applications: VMA Single Duct Click OK. 2 VMA Controller VMA Demo Unit
7. To build the question-and-answer session, select all default answers by repeatedly pressing the Enter key. After the last question and answer, the default question-and-answer list appears in the left window of HVACPRO for Windows. The corresponding parameters are listed in the right window. 8. In the Parameters window of HVACPRO for Windows, scroll to the Flow Configuration group. Double-click on it (if needed) to expand it and view the sub topics. Double click on each of the following parameters and change them to the values listed here: Area = 0.1 Pickup Gain = 2.000 Cooling Max. Flow = 200 Occ. Cooling Min. = 25 Unocc. Cooling Min. = 0 Warmup Min. Flow = 50 Min Delta V p = 0.0 cfm Max Velocity = 200.0 9. From the File > Save As menu, click OK on the Target Device Selection screen. Save the current configuration as demo.cfg in the default directory. 10. Download the current configuration to the VMA using the MM-CVT101-0 converter. Make sure the N2 converter connector is plugged into the lower three positions (REF, N2-, N2+) on the VMA. VMA Controller VMA Demo Unit 3
Demonstration To demonstrate the VMA Demo Unit: 1. Turn on the demo unit fan power and allow it to run for 1 minute to stabilize VMA control. 2. In the Options menu, select View > Commissioning. 3. In the Commission menu, select Commission Current Configuration. 4. In the Commission Controller dialog box, enter the VMA N2 address. Check the DIP switches on the VMA unit to confirm the address is correct. 5. When the Commission mode is active, find the Flow Status group in the Parameters list. Flow Status should show three parameters: Present Value, Process Variable, and Setpoint. 6. From the HVACPRO for Windows Commission menu, select Data Graphing. 7. In the Data Graphing - Point Selection dialog box, highlight and add the following parameters: Graph 1 Points - Flow Status, Setpoint - Flow Status, Process Variable Graph 2 Point (omit if not applicable) - Flow Status, Present Value Figure2 Figure 2: Point Selection Dialog Box 4 VMA Controller VMA Demo Unit
8. Click OK to switch to the Data Graphing window. Note: If the file for logging data already exists, the following appears: Contents of file will be Overridden. Continue? Select Yes. 9. Double-click the edge of the vertical scale line (left side) to set Data Graphing scaling. Figure3 Figure 3: Data Graphing Screen VMA Controller VMA Demo Unit 5
10. Set the vertical axis limit to 150 cfm. Figure4 Figure 4: Vertical Access Dialog Box 11. Set the Ticks, Step value to 25. 12. Click OK. 13. Arrange HVAC PRO for Windows Commissioning and Data Graphing windows so both the Parameters list and Data Graph are visible. 6 VMA Controller VMA Demo Unit
Figure5 Figure 5: Commissioning and Data Graphing Windows 14. Allow graphing to run for a few minutes to track present value. 15. In the HVAC PRO for Windows Parameters window, override the flow status setpoint to 50 cfm. Note: When overriding setpoint value, stay within box/fan maximum cfm limit. 16. Observe Process Variable (PV) response curve graph. A large setpoint change will cause the PV to respond as if in proportional only control. As PV nears setpoint, P-Adaptive slows response. Overshoot is nearly non-existent. Within seconds of setpoint change, PV is at new setpoint. 17. Repeat Steps 15 and 16 several times with different values. VMA Controller VMA Demo Unit 7
Notes Controls Group FAN 636.3 507 E. Michigan Street Application Specific Controllers Technical Manual P.O. Box 423 Printed in U.S.A. Milwaukee, WI 53201 www.johnsoncontrols.com 8 VMA Controller VMA Demo Unit