AutomatedBuildings.com Article - Using the BASrouter with a Honeywell Spyder Controller

Contemporary Controls’ BASrouter provides a simple, cost-effective method to attach Honeywell Spyder BACnet MS/TP controllers to BACnet/IP without the need of a building controller. This allows Spyders to reside on the building’s Ethernet network without the need to provide home-run fieldbus wiring to a head-end. Spyder controllers are frequently used for both VAV and unitary applications. Originally available as a LON device, they are also available as a BACnet MS/TP device and therefore can be easily integrated to BACnet/IP with the popular BASrouter.

Installing and operating the BASrouter (BASRT-B) with several Honeywell Spyder controllers is simple and straightforward. Configuration of the BASrouter is accomplished through web pages. Once the BASrouter is properly installed and configured, all the connected Spyder controllers can be accessible from any BACnet/IP client device.

In addition, the BASrouter supports three-way routing between BACnet/IP, BACnet Ethernet and BACnet MS/TP. Any two or all three protocols can be routed, thereby allowing the system integrator to mix BACnet network technologies within a single BACnet internetwork. As an aid to troubleshooting, a diagnostic page will display the number of messages received and sent for each of the protocols supported.

Spyder Controllers

Honeywell manufactures several Spyder BACnet MS/TP controllers for unitary and VAV applications that can be accessible from BACnet/IP once the BASrouter is in place. The following information is applicable to each BACnet MS/TP model.

BACnet MS/TP data from the Spyder controllers are carried over a two-wire non-isolated twisted-pair network. Spyder controllers auto-baud. They wait until a head-end device — usually a building controller — to send out frames so connected controllers can “wake-up” and set their speed to that of the building controller.

The BASrouter takes the place of the building controller so its data rate must be set during configuration thereby allowing the Spyder controllers to automatically match their data rate with that of the BASrouter.

A typical wiring diagram is shown. Like the BASrouter, the Spyder controllers incorporate a 24 VAC half-wave rectified power supply meaning that the BASrouter and the Spyder controllers can share the same AC power source as long as the COM pin on the BASrouter and the 24VAC COM pin on the Spyder controllers are connected together as shown. If separate power sources are used then an earth connection must be shared by the COM and 24VAC COM pins. The BASrouter requires about 4 VA of power while Spyder controller consumption varies with the model. Verify that adequate power is available when sharing a transformer. Notice the grounding requirements in the wiring diagram.

The Spyder controllers utilize a two-wire, non-isolated MS/TP network while the BASrouter supports a 3-wire isolated MS/TP network. If possible, install the BASrouter at one end of the MS/TP segment. This will be called the near-end. Follow Honeywell cabling and grounding recommendations. Notice that Honeywell requires that the shield be carried to the head-end where it is then earthed. Connect the data pair as shown observing polarity. A common ground reference is required in order for the MS/TP transceivers to operate properly. Connect the SC pin and the COM pins together on the BASrouter. Make sure an earth connection exists between all the controllers and the BASrouter when separate power sources are involved. This helps protect the data lines from excessive common-mode voltages that could damage the transceivers or create data errors. Although the Spyders utilize 1/4 EIA-485 load transceivers, it is recommended not to exceed 63 controllers on a network. The BASrouter consumes one load. If possible, try to limit the network to about 45 controllers to improve responsiveness. Apply a 120-ohm terminator to the last controller on the far-end of the MS/TP segment. The BASrouter has internal bias and termination applied (default configuration) so the near-end is already terminated and should not receive an external terminator. Do not apply any external bias. If the BASrouter is installed mid-span, termination and bias can be disabled by removing three jumpers inside the BASrouter. In this situation, external bias and termination would need to be applied at the near-end while external termination is applied to the far-end. A mid-span installation of the BASrouter is discouraged. However, if no bias source exists on the bus the BASrouter can supply this bias by reinstalling the outer two jumpers.

Configuring the BASrouter

Configuring the BASrouter with a web browser is straight forward. Both the BACnet/IP and MS/TP sides of the router need to be configured. The following settings apply to the BASrouter itself.

A unique Device Instance must be assigned to the BASrouter. If you are only connecting to a BACnet/IP network and not to a BACnet Ethernet network, leave the Ethernet Network number at 0.

Typically, use the BACnet/IP UDP Port default of BAC0. Set the IP Address, Subnet and Gateway accordingly.

For the MS/TP MAC address of the BASrouter, we suggest the default of 0. However, this is the default address for all Honeywell MS/TP devices — so all Spyders should be set to a different address before attaching them to the network. MAC address 0 gives the router the first opportunity to grab the token. Select a unique MS/TP Network for the MS/TP segment. Set Max Master to 127 since the default setting of the Spyder is 127. This can be changed using the Spyder tool. The Max Master settings should be the same for all devices on the network. Max Info Frames are not critical. Select a value between 30 and 100.

Spyder controllers auto-baud, meaning they remain silent until a device, such as a building controller, begins sending frames. Once traffic is sensed, the Spyder controllers match their data rate to that of the traffic. Instead of a building controller, a BASrouter is used. Set the MS/TP Baud rate to a typical rate such as 38,400 or 76,800. For MS/TP Tolerance, select Lenient.

Do not bother with the Advanced screen unless you must enable the BBMD feature for IP router traversal. Consult the BASrouter application guide for more information on sub-netted networks. When you are finished with the settings, save the changes.

Consult Honeywell publication 62-0310-01 for installation instructions.

Using BDT to verify MS/TP Communication

The BACnet Discovery Tool is a BACnet/IP application for Windows® that is easy to install and use. It is an excellent means for discovering and verifying communication with MS/TP devices that are being accessed through BACnet/IP routers such as those available from Contemporary Controls: the BASRT-B DIN-rail mounted BACnet/IP-to-MS/TP router — or its portable counterpart, the BASRTP-B. At Contemporary Controls we use BDT with equipment from different BACnet vendors to prove our routers operate with different equipment configurations.

It can be downloaded for free at www.ccontrols.com/sd/bdt.htm.

Using the Search function, BDT transmits BACnet Who-Is messages and a progress bar appears.

When BDT has completed its search, the progress bar will disappear, the discovered BACnet devices will be listed in the main window and the number of discovered devices will be reported in the Devices Discovered field — similar to the display below.

About the Author

George Thomas is president of Contemporary Controls with headquarters in Downers Grove, Illinois. For over 35 years, Contemporary Controls has been designing and manufacturing the system building blocks used to automate buildings, machines and processes. Contemporary Controls has manufacturing locations in the United States and China, and additional support offices in the United Kingdom and Germany. George Thomas received his BSEE and MSEE degrees from the Illinois Institute of Technology. He is a life senior member of IEEE and a senior member of ISA. He currently serves on the BACnet International Education Committee.

For more information, visit www.ccontrols.com, or email info@ccontrols.com.

You can also find Contemporary Controls at http://www.facebook.com/ContemporaryControls and http://twitter.com/ContempCtrls.

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