Help identifying a M12-like 4-pin connector with 6mm diameter
M12 connector IEC 61076-2-101

plug, circular  4-position, shielded, Plug straight M12, D-coded, Crimp connection, Knurl material: Zinc die-cast, nickel-plated, External cable diameter 5 mm ... 8 mm

e.g. http://media.digikey.com/pdf/Data%20Sheets/Phoenix%20Contact%20PDFs/1411046.pdf  no stock

or http://www.digikey.com/product-detail/en/hirose-electric-co-ltd/HR10A-7P-4PC(73)/HR1663-ND/1095521  then add contacts