Fieldbus coupler for PA/FF segments
The Siemens 6ES7157-0AC85-0XA0 is a Field Device Coupler that bridges PROFIBUS DP to PROFIBUS PA or Foundation Fieldbus H1. It provides an integrated bus supply up to 1 A for up to 31 field devices, with redundancy capability. Operates from -40 to 70 °C ambient, per the datasheet. Power loss is 13.4 W typical at 24 V DC. The supply voltage range is 20.4 to 28.8 V DC, with reverse-polarity protection and a hold-up time of 5 ms on mains failure.
Mounting and wiring notes
Galvanic isolation is tested at 600 V DC between supply and all other circuits, as well as between DP, PA, and backplane bus. Overvoltage protection is included.
Diagnostic indicators
Onboard LEDs report group error (red), bus fault BF (red), bus activity on DP (yellow) and PA (yellow), plus supply voltage OK (green). A diagnostics function is additionally available via the DP protocol.