Knowledge Base

The board can connect to your controller in one of two ways: Via the 2 pin TTL Xwire connector or via an RS485 adaptor, if your controller does not have an RS485 Xwire interface. You have to decide which interface you are using, select it via a jumper and then connect to the corresponding external terminals.

Xwire is our proprietary serial peripheral bus. It consists of the Xwire electrical interface and the Xwire data protocol that is used to convey data across the interface and wiring. The 2 pin TTL Xwire electrical interface is good for a few feet and up to 10 boards. The final choice of interface is dependent on the distance and the electrical environment (ie: the amount of electrical noise).

RS485 is an industry standard electrical interface suitable for direct wire connection between devices located up to hundreds of feet apart. RS485 will allow up to 32 boards to be connected. The programming is the exactly same but you will be able to go further for the cost of an extra RS485/Xwire converter on the controller. The RS485 interface is more forgiving in terms of noise and is better protected against electrical transients.

Selecting the Xwire or RS485 interface

A 3-pin jumper in the middle of the board is labelled ‘RS485 X‘. Inserting a jumper in the two pins labelled RS485 will activate the RS485 interface. Inserting a jumper in the two pins labelled X will activate the TTL Xwire electrical interface.

Connecting to the Xwire interface

Two connectors on one long side of the board are labelled X1 and X2. These are the TTL Xwire electrical connections. The two connectors are wired in parallel on the board to facilitate daisy chaining, and are completely interchangeable. The left-hand pin of each connector is ground (0V). If you are wiring to other boards with X1/X2 connectors, simply wire like pins together. If wiring to MMi202 or SL100, see the Xwire connection instructions in their documentation. See also wiring in the Xwire documentation.

Connecting to the RS485 interface

The 3-pin screw terminal block is for RS485 connection. The A and B terminals should go to A and B on all other devices on the RS485 system. The G terminal should go to system ground. Just next to the terminals (to the left above) is a jumper marked “Term”. Installing a jumper in that position provides an RS485 line terminator.

TN9301 interface

The TN9 connector provides an interface to an optional TN9301 peripheral board. The TN9301 provides 2 temperature readings. The first will be a ranged temperature reading of the target that the TN9301 is currently pointing at. The second will be the ambient temperature coming from the area immediately around the TN9301 itself. Key specifications for the TN9301 can be found in the TN9301 Specification section of the SPLat Knowledge Base.