Parker IQAN-MC31 Instruction Book

22Digital inputsInstruction book, IQANDigital inputsDIN that share pins with VINThese digital inputs share pins with the module voltage inputs and have highimpedance characteristics. The preceding switch examples apply to these inputs.DIN that share pins with CRETThese digital inputs share pins with the return pins of the proportional output channels,e.g. CRET and PWMRET. These pins have an internal power clamping diode. If usedas inputs they must be connected in a way that prevents ’backending’, that is, supplyingpower to the module from a source other than its power pin (+BAT).Carefully read the following section for more information.Connecting switches to the digital inputsWhen connecting switches to the digital inputs, DIN, that share pins with CRET, extraprecautions should be taken.W ARNINGThe DIN that share pins with the CRET positions of the proportional outputs have apossibility of ’backending’ the IQAN module when using those pins as digital inputs.The internal circuitry has power clamping diodes between CRET pins and the internalpower supply. This arrangement creates a risk of inadvertently supplying power to theunit.You can safely connect using +VREF for the supply, as shown in the preceding"Connecting switches to the voltage inputs" example.If you would like to preserve +VREF for sensors and joysticks, then there are twoadditional methods:1 The switches could be powered by one of the module’s DOUT pins.EXAMPLEConnect the supply of the switch to DOUT-X, and the signal to DIN-X , respectively.Connecting a switch to DOUT-X and DIN-X.DIN-XDOUT-XIQAN moduleswitch