CTI 2500-RBC (901E-2500-RBC) Profibus Remote Base Controller
Brand: Control Technology Inc. (CTI)
Model: 2500-RBC
Part Number: 901E-2500-RBC
Full Product Name: Profibus Remote Base Controller (RBC)
Overview
The CTI 2500-RBC is a Profibus DP remote base controller for the classic CTI 2500 series PLC system. Once plugged into an I/O rack, this module converts the entire CTI 2500 series or Simatic 505 I/O base into a Profibus DP slave node for connection to the Profibus fieldbus network. It enables distributed remote I/O data acquisition and output control.
As a direct replacement for the Siemens 505-6870 RBC, it is widely deployed for legacy system upgrades and DCS/PLC retrofitting. Existing 505 I/O bases and I/O modules can be retained without replacing field I/O hardware, cutting renovation workload and project costs.
This rack-mount plug-in module features an LED digital display on the front panel to show station addresses and fault diagnostic codes. It is equipped with a Profibus DB9 female bus port. On-board DIP switches set the Profibus slave address and display mode. It also supports configurable output states upon communication failure: all outputs off or hold last value, meeting safety logic requirements for industrial sites.
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Key Features
- Profibus DP Slave: Compliant with Profibus DP standard. Compatible with Siemens S5/S7 and other mainstream Profibus master systems. Works with CTI 2500 series and Simatic 505 I/O bases, supporting 4-slot, 8-slot and 16-slot CTI / Siemens 505 racks.
- Full-range I/O Compatibility: Supports all digital and analog I/O modules from CTI and Siemens 505 series. Existing I/O points and wiring remain unchanged for simple retrofits.
- Communication Baud Rate: Multiple selectable rates from 9.6 kbps to 12 Mbps
- 9.6 kbps: Max segment cable length 1200 m
- 12 Mbps: Max segment cable length 100 m
- Electrical Isolation: 1500 VDC isolation on Profibus interface for enhanced on-site noise immunity and protection for the bus and control system.
- Fail-safe Selection: Hardware jumper selects behaviour on communication loss: all outputs OFF or freeze and hold the current value.
- Configuration Support: Original manufacturer GSD file available for slave station setup and I/O slot configuration via WorkShop, ComProfibus and other software.
- Local Diagnostics: On-board LED digital tube displays Profibus station number, bus faults and module error codes for fast on-site troubleshooting.
- Hardware DIP Switches: Set Profibus station address, display mode and reserved serial baud rate.
Technical Specifications
- Bus Interface: Profibus DP, DB9 female connector
- Isolation Rating: 1500 VDC isolation on Profibus port
- Baud Rate Options: 9600, 19.2K, 93.75K, 187.5K, 1.5M, 3M, 6M, 12M
- Supported Racks: 4/8/16-slot CTI 2500 / Simatic 505 I/O bases
- Configuration File: Supplied with GSD file (V3.0~V3.9)
- Mounting: Backplane bus plug-in, powered by base backplane
- Diagnostics: 3-digit LED digital display + status LEDs
- Safety Mode: Output OFF or value freeze via jumper selection when communication is lost
Applications
- Retrofit & upgrade of legacy Siemens 505 PLC systems in chemical, power and metallurgy industries
- Distributed Profibus remote I/O station construction for scattered field signal acquisition
- Expansion of existing CTI 2500 control systems for steam turbines, generator sets and production lines
- Technical renovation projects where original field I/O modules and wiring are kept, only the communication controller is replaced
FAQ
Q1: What is CTI 2500-RBC (901E-2500-RBC)?A: CTI 2500-RBC (Part No. 901E-2500-RBC) is a Profibus DP remote base controller within the CTI 2500 series. It is NOT an independent PLC. Its function is to convert a complete CTI 2500 / Siemens 505 I/O rack into a Profibus DP slave to implement distributed remote I/O communication.
Q2: Which racks and I/O modules are compatible?A: It supports 4-slot, 8-slot and 16-slot CTI 2500 and Simatic 505 I/O bases. Original CTI and Siemens 505 digital and analog I/O modules can be used directly. Existing field wiring stays untouched, ideal for legacy system retrofits.
Q3: What Profibus baud rates and communication distances are supported?A: Baud rate ranges from 9.6 kbps to 12 Mbps. At 9.6 kbps, the maximum single-segment bus distance reaches 1200 m. At 12 Mbps high-speed mode, the maximum single-segment distance is 100 m. It works with all types of Profibus masters.
Q4: What happens to I/O outputs when communication drops?A: An on-board hardware jumper selects two fail-safe modes. When communication is lost, outputs can be fully switched OFF or retain their last value. Configure according to process safety requirements.
Q5: Does the Profibus interface have electrical isolation?A: Yes. The Profibus DB9 communication port provides 1500 VDC electrical isolation, separating the bus side from the I/O backplane circuit. It improves noise resistance in industrial environments and protects modules and bus devices.
Q6: Is a GSD file required for configuration?A: Yes. The OEM GSD file is provided. It can be imported into Siemens STEP, ComProfibus, WorkShop and other configuration software to recognise the Profibus slave and set up rack slots and I/O points.
Q7: How to perform module fault diagnosis?A: The front panel has a 3-digit LED digital tube plus status indicators. It shows real-time Profibus station address, bus error codes and module runtime faults for engineers to quickly locate communication or hardware issues. The station number is set by on-board DIP switches.
Q8: What are the main application scenarios?A: It is commonly used for legacy Siemens 505 PLC retrofits in chemical, power and metallurgy, control system expansion for steam turbines and generator sets, and building distributed Profibus remote I/O stations for factory production lines. Its biggest advantage is preserving original I/O hardware to greatly reduce renovation time and costs.
