Select I/O is an Ethernet networked, single channel granular I/O system for the ABB Ability™ System 800xA automation platform. Select I/O helps decouple project tasks, minimizes the impact of late changes, and supports standardization of I/O cabinetry ensuring automation projects are delivered on time and under budget. A Signal Conditioning Module (SCM) performs the necessary signal conditioning and powering of the connected field device for one I/O channel.

The AOS850 is an Analog Output Signal Conditioning Module (16-bit) for use in Intrinsically safe applications (Zone 0) supporting 2-wire field devices and HART communications.

• Analog output for 2-wire field devices
• Signal range: 0…20 mA or 4…20 mA
• Can be used in hazardous areas
• 16 bit D/A converter
• Channel to channel galvanic isolation
• Configurable output rise/fall times (down to 1 ms; with HART down to 20 ms)
• Protected against wrong wiring
• Diagnostics:
  • Loop supervision (open circuit and short circuit)
  • Hardware error supervision
  • Communication supervision
  • Internal power supervision
• Support of HART field devices (up to HART application layer rev. 7):
  • HART Pass-Through
  • Cyclic read of up to two HART Device Variables
  • HART Device Validation
• OSP (Output Set to Predetermined value)
• Single loop granularity – each SCM handles a single channel
• Supports hot swap
• Mechanical locking slider which turns off field device power and/or output before removal
• Field disconnect function which can galvanically separate the field loop wiring from the SCM during commissioning and maintenance
• All SCMs have electronic current limitation
• Mechanical keying to prevent insertion of wrong module type after commissioning
• 24V DC powered through Modulebus
• Configurable through parameters
• LED indicators on the SCM indicate the operational state of the module