text: <s>[INST] 1756-HSC Do we have to tie the 24vdc common to card and if so where do we do that? [/INST] It depends... if you have a Differential Line Driver encoder, you don't need 24 Vdc common.If you use a different source, the Common should be connected to the RET terminal of the input you use (A,B). Aid 41188 See also the screenshot below from User Manual . Hope this helps... - fuzzy logic \\n </s>