You need a universal counter, not a frequency counter. SDG2000x is neither of these, it's an arb. B&K 1823A, Iwatsu SC-7205 and Agilent 53131A have totalize mode and RS232 connectivity. TTI TF930 has totalize mode and USB. Picotest U6200A / Berkeley Nucleonics 1105 and Keysight 53220A have totalize mode, USB and Ethernet (hold on to your wallet). You could also DIY it.