User's Manual

40
Figure 2.14 – NEMA TS-2 Rack Channel to Traffic Phase Example
In Figure 2.14, four channels are used from each SmartSensor Matrix unit. In this
example, channel 1 from the first sensor is mapped to traffic phase 1 (left-turn
phase on main street). Channels 2, 3, and 4 from the first sensor are mapped to
traffic phase 6. This represents a case where detections from three through-
movement lanes are brought in separately. This type of lane-by-lane detection is
beneficial in some situations. Wavetronix typically recommends the use of 4-
channel cards in racks that will accommodate them, because it offers greater
flexibility of signaling contact closures.
Figure 2.15 illustrates how the detector channels 1 to 8 of a NEMA TS-1 rack can be
assigned to the standard 8-phases using four Click! 112 cards. The rack card slots
are numbered across the top and the channel positions are represented by the gray
labels C1 – C8. This example has the economy of only using four rack slots, but it
does not provide lane-by-lane signaling of the through-movement for cases where
there are multiple through lanes. If you are using a rack with a two-channel
dominant scheme (Four channel cards are not allowed and channels 1 and 2 are in
Note
The channel positions in Figure 2.14 are representative of their arrangement
when two-channel cards are used, even though four-channel cards are
depicted in this example. In reality, all the channels of a four-channel rack
card are signaled through the backplane contacts connected into the in the
even numbered rack slots. NEMA TS-2 channel order is based upon a four-
channel dominant scheme, instead of two-channel dominant scheme. A four
channel dominant scheme will allow two-channel or four-channel cards to be
inserted, but the numbering is based upon a four-channel card. This is why
channels 1 and 2 are in slot 2, instead of slot 1.