ABB S900 I/O Module – ABB PLC‘s DCS’s Systems

S900 is a remote I/O system for mounting directly in the field and hazardous areas.
S900 provides all input and output modules needed for intrinsically safe field signal connection. The field signals are amplified in every S900 functional module, electrically isolated, and then output via an internal serial bus. A communication interface converts the digitized signals to adapt them to the standardized PROFIBUS DPV1 fieldbus protocol. Supervisory process control systems, DCS or SCADA systems use an intrinsically safe fieldbus to communicate with the communication interface.
A single fieldbus network suffices for configuring the individual fieldbus nodes, for cyclic data exchange, for all acyclic services, and for communication with HART®-compatible field instruments. All functional modules can be replaced easily and quickly in the installation or maintenance phase. The functional modules and the – optionally redundant – communication interfaces of systems placed in Zone 1 can be removed and plugged in while operation is running, without affecting the communication of the remaining modules. Only the primary power for the plug-in type power supply modules requires increased safety EEx-e.
Integrated encapsulated switch-off mechanisms allow for hotswapping, i.e. the power supply units can be replaced without interrupting the primary power. Due to its little space requirements and robust design and its environmentally ruggedized case, the I/O system S900 is the best, cost-saving so


  • Value for your money: Integrated galvanic isolated barrier function reduces the need for additional barriers
  • Simplified maintenance thanks to auto-diagnostics and the availability of diagnostic data via the fieldbus or locally at the S900 I/O station
  • Easy configuration using FDT/DTM or GSD files
I/Os for Freelance overviewS900 I/O can also be used in hazardous areas.


Ready-made, EExi/ATEX-certified high-grade steel housings and the CB220 Compact Box for assembly in the field provide a wide range of installation options.

Field housings – for wall-mounting in the case of installation in Zone1 with a system approval fully certified in accordance with ATEX. The stainless steel field housing is ready-wired and prepared
for wall-mounting. In addition, screen rails or terminals can be mounted. Together with the field housing, this brings the following advantages:

  • Complete design, heat compensation, and documentation by ABB
  • Elimination of additional marshalling units
  • Thanks to the S900 modules, no external barriers are needed for the field circuits
  • Simplified acceptance of the plant with regard to hazardous areas

CB220 compact box – S900 remote I/O in compact form with up to 4 I/O modules for decentralized use in a compact housing. This variant is suitable, for example, for use in applications such as temperature multiplexers and solenoid controls. The CB220 compact box additionally offers the following advantages:

  • Compact design
  • Easy field assembly
  • Decentralized assembly makes it possible to cut down on wiring

We focus on industrial automation and process instrument!


Distributed signal acquisition has become more and more accepted in the field of process engineering. With S900 ABB offers an eco-efficient remote I/O system with redundant networking capability.

Analog Input (4 channels)

Description Non Ex Ex Zone 2 Ex Zone 1
Transmitter power supply,
Analog Input
4…20 mA
S900-AI910N S900-AI910B S900-AI910S
Transmitter power supply,
Analog Input, HART
4…20 mA
S900-AI930N S900-AI930B S900-AI930S
Passive Analog Input, HART
0/4…20 mA
S900-AI931N S900-AI931B S900-AI931S

Analog Output (4 channels)

Description Non Ex Ex Zone 2 Ex Zone 1
Analog output
0/4…20 mA
S900-AO910N S900-AO910B S900-AO910S
Analog output, isolated
0/4…20 mA
isolated outputs channel by channel
S900-AO920N S900-AO920B S900-AO920S
Analog output HART
0/4…20 mA
S900-AO930N S900-AO930B S900-AO930S

Digital Input/Output

Description Non Ex Ex Zone 2 Ex Zone 1
Digital Output for I.S. valves
(4 channels)
S900-DO910N S900-DO910B S900-DO910S
Digital Input or Output
input for dry contact or NAMUR initiator
output for low power I.S. valves
(8 channels)
S900-DX910N S900-DX910B S900-DX910S
Relay module for digital signals
(6 channels)
S900-DO930N none none

Temperature (4 channels)

Description Non Ex Ex Zone 2 Ex Zone 1
Pt100, Pt1000, Ni100 in 2-/3-/4-technology thermocouples type B, E, J, K, L, N, R, S, T
isolated inputs channel by channel
S900-AI950N S900-AI950B S900-AI950S

Frequency Input (2 channels)

Description Non Ex Ex Zone 2 Ex Zone 1
input for dry contact or NAMUR initiator S900-DP910N S900-DP910B S900-DP910S

Communication Modules

Description Non Ex Ex Zone 2 Ex Zone 1
Communication Interface
S900-CI920N S900-CI920B S900-CI920S
Intrinsically safe PROFIBUS-DP connector standard connector S900-BP910S S900-BP910S

Fieldbus isolating repeater
separates an intrinsically safe RS485 fieldbus from a non intrinsically safe

Description Ex Zone 1
RS485 fieldbus without bus termination
mounted in DIN railmounted housing with IP20 protection
RS485 fieldbus with bus termination
mounted in DIN railmounted housing with IP20 protection
Fieldbus isolating repeater RS485 / fiber optic ring Master/Slave S900-BI924S (Master)
S900-BI923S (Slave)


Description Non Ex Ex Zone 2 Ex Zone 1
Power supply filter
One filter is necessary for powersupply with Catalog No. SA910S
CD-ROM / S900 Software-Tools / Documentation
CD-ROM / DTM f0r fieldbus devices
CD-ROM / Fieldbus project tool
>>see list 63
Field housing, stainless steel (1.43.01) S900-FH660S-0000 (empty box) S900-FH660S-xxxx Series (certified, incl. wiring)
S900-FH680S-0000 (empty box) S900-FH680S-xxxx Series (certified, incl. wiring)
Insert labels
320 pcs.
S900-IL910 S900-IL910 S900-IL910
Module housing
IP20 protection for empty slots on the termination unit
Power Supply S900-SA920N S900-SA920B S900-SA920S
Redundant Termination Unit
for 16 I/O-modules
redundant communication and power
S900-TU921N S900-TU921B S900-TU921S

Compact Box CB220

Description Non Ex Ex Zone 2 Ex Zone 1
Power Supply, only for CB220
for 24 V DC
S900-SA911N S900-SA911B S900-SA911S
Compact BoxThe compact box connects 4 I/O modules, 1 power supply and 1 communication module, IP66 (nema 4). S900-CB220N S900-CB220B S900-CB220S
Modules and Communication Interfaces see tables above