By plugging the optional DP-OPT-CARD-IP-mA card in the DIGICHEM Plus+ controller, you have the additional features of 2 x 4-20mA inputs and 6 contact alarm inputs. The 4-20mA inputs are ideal for monitoring Corrosion rates for up to 2 metals utilising the DP-OPT-LOGR corrosion monitors with 4-20mA outputs. The corrosion rates can then be trended on the multi-parameter graphs on www.digichemplus.com. The contact inputs are typically used to detect low chemical level in tanks with low level floats. The contact state change in the level switch triggers a low chemical alarm distributed via email and/or SMS. Please note that a 4G modem is required to be installed in the DIGICHEM Plus+ controller too in order to receive alarms.