Setting the device address - Metasys - MS-VMA1826-x - MS-VMA1832-x - Field Device - VMA18 VAV Modular Assembly

VMA1826/1832 VAV Controller Installation Guide

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VMA18 VAV Modular Assembly
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Installation Guide
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Metasys field controllers are subordinate devices on N2 buses. Before operating field controllers on a bus, you must set a valid and unique device address for each controller on the bus.

You set a field controller’s device address by setting the positions of the switches on the Device Address DIP switch block at the top of the controller ( Figure 1 ). Device addresses 1 through 253 are the valid N2 addresses for these N2 controllers.

Valid MS/TP addresses for wired controllers are 4 through 127. For wireless controllers, valid addresses are 132 through 254 (132 [132-128=4] through 254 [254-128=126]).

For wireless controllers, the address 120 through 127 are used by the ZigBee® Coordinator. This may cause a smaller field device range.

If the VMA18 Series controller may eventually be converted to MS/TP, use addresses 4 through 127 for a wired VMA controller or addresses 132 through 253 for a future wireless VMA controller, if possible. Using these addresses simplifies the MS/TP conversion process.

Note: Metasys field controllers ship with Switch 128 ON and the remaining address switches OFF rendering the controllers wired subordinate devices, which do not operate on MS/TP buses, but do not interfere with bus operation. Set a valid and unique device address on the field controller before applying power to the controller on the bus.

The DIP switch block (Figure 1) has eight switches numbered 128, 64, 32, 16, 8, 4, 2, and 1. Switches 128 through 1 are device address switches.

Figure 1. Device address switches set to 21

To set the device addresses on a Metasys field controller:

  1. Set all of the switches on the field controller’s device address DIP switch block (128 through 1) to OFF.
  2. Set one or more of the eight address switches (128 through 1) to ON, so that the sum of the switch numbers set to ON equals the intended device address. Set the highest number switch that is less than or equal to the intended device address to ON. Then continue setting lower numbered switches until the total equals the intended address. For example, if the intended device address is 21, set Switch 16 to ON first, then set Switch 4 to ON, followed by Switch 1 (16+4+1=21). See Figure 1.
  3. Set a unique and sequential device address for each of the field controllers connected on the N2 bus, starting with device address 1. To ensure the best bus performance (if the protocol is changed to BACnet MS/TP), set sequential device addresses with no gaps in the device address range (4, 5, 6, 7, 8, 9, and so on). The field controllers do not need to be physically connected on the bus in their numerical device address order.
  4. Write each field controller’s device address on the white label below the DIP switch block on the controller’s cover.

Refer to the N2 Communications Bus Technical Bulletin (LIT-636018) for more information on field controller device addresses and how to set them on N2 buses.