BSL PRO Software Guide - Biopac

114 Part CControl dialog and graph showing control channel with “wide” thresholdIt is also possible to have the digital line switch when the source channel drops below a certain value. In the examplebelow, a simple threshold is used to switch the digital line high each time the source channel drops below 50 BPM.Since L2 and L1 are set to the same value, this is not a “wide” threshold (as above) and the threshold resets eachtime the source channel goes above 50 BPM.Control dialog and graph showing control channel detecting source channel levels less than 50 BPMThese examples are only a few of the possible applications of the control channel using the two threshold icons onthe left-hand side of the Control Setup dialog. You can construct variations of these (i.e., switching the digital linefrom low to high using a wide threshold whenever the source channel drops below a given channel) that are notdiscussed above. Moreover, each of the options can be construed somewhat differently than they have beenpresented here. For example, the previous example switches the digital line from low to high each time the signal onthe source channel drops below 50 BPM. Conversely, it also switches from high to low each time the source channelvalue is greater than 50 BPM. This allows you to vary the default setting for the digital channels (whether the defaultis zero or +5 Volts) depending on what types of devices are connected.In addition to setting “above and below” type thresholds, you can program the Control channel such that the digitalline is switched whenever the source channel falls within a given range or outside a specified range. In the examplethat follows, digital line 15 is set to switch from zero to +5 Volts whenever the source channel signal falls betweenthe values entered in the L1 and L2 boxes. In this case, I/O is switched to +5 Volts whenever the heart rate is greaterthan 60 BPM but less than 80 BPM.Visit the online support center at www.biopac.com