Yokogawa 2-Wire Analyzer FLXA21-D-P-D-AB-C1-NN-P-N-LA-N-NN/U/H6/SCT/CD4 The FLXA21 is 2-wire module-type liquid analyzer that can be connected to up to two detectors from pH /ORP meters, conductivity meters, inductive conductivity meters, and dissolved oxygen meters.