Description
Pepperl+Fuchs MB-C3-AI16-KS-131961 (7605)
Product Introduction
The Pepperl+Fuchs MB-C3-AI16-KS-131961 is a 16-channel analog input termination motherboard developed for Yokogawa control-system installations. Its primary function is to provide the physical and electrical interface between compatible Pepperl+Fuchs signal isolators and the Yokogawa DCS. The board accepts up to 16 plug-in isolator positions and is documented for Yokogawa analog input applications using AAI141 and AAI143 interfaces. It is therefore important to classify this product correctly: Pepperl+Fuchs MB-C3-AI16-KS-131961 is a termination and interface assembly, not the analog measurement electronics itself.
The board is designed around Pepperl+Fuchs K-System isolators, with KFD2-STC4-Ex1 identified as the recommended analog-input module where HART communication is required. KFD2-UT2-Ex1 is also supported for analog input applications, but the documentation notes that this configuration does not provide HART communication. The motherboard uses a 24 VDC supply, field-side screw terminals, and a 40-pin Yokogawa system connector toward the control-system side. A separate 26-pin connection provides the HART communication path when compatible modules are installed.
From an engineering standpoint, Pepperl+Fuchs MB-C3-AI16-KS-131961 is most relevant where an existing Yokogawa installation uses Pepperl+Fuchs intrinsic-safety interfaces for analog transmitters. The board simplifies the physical organization of multiple channels while maintaining the required field wiring and DCS-side connections. The published mechanical drawing identifies the assembly as a 16-channel redundant analog-input motherboard. Replacement work should therefore verify the existing isolator type, Yokogawa I/O card, system connector, HART requirement, and wiring arrangement rather than treating the board as a generic analog-input termination panel.
Technical Specifications
| Specification | Details |
|---|---|
| Product Model | MB-C3-AI16-KS-131961 (7605) |
| Manufacturer | Pepperl+Fuchs |
| Product Type | Analog Input Termination Board / Motherboard |
| Application | Yokogawa control systems |
| Channel Capacity | 16 plug-in module positions |
| Supported Function | Analog Input |
| Recommended Isolator | KFD2-STC4-Ex1 |
| Alternative Isolator | KFD2-UT2-Ex1 |
| HART Support | Yes, with compatible HART isolator configuration |
| Supply Voltage | 24 VDC |
| Field Interface | Screw terminals |
| DCS/System Interface | 40-pin Yokogawa system connector |
| HART Interface | 26-pin flat cable connector |
| Mounting | Motherboard/termination assembly; system installation dependent |
| Board Dimensions | Approximately 325 × 150 mm according to mechanical drawing |
| Redundancy | 16-channel redundant motherboard configuration |
| Fuse Arrangement | Two 2 A motherboard supply fuses |
| Alarm Contact | Up to 30 VDC, 1 A |
| Compatible Yokogawa AI | AAI141 / AAI143 configurations |
| Operating Temperature | -20 to +60 °C listed by secondary product documentation |
| Part Number | 131961 / 7605 |
The 16-position arrangement, 24 VDC supply, 40-pin system connection, 26-pin HART connection, fuse arrangement, and compatible isolator information are documented in the Pepperl+Fuchs technical material.
MB-C3-AI16-KS-131961
Main Features and Engineering Considerations
1. 16-channel analog input architecture
The MB-C3-AI16-KS-131961 provides 16 positions for compatible analog-input isolator modules. The board itself should not be substituted for the actual K-System isolators. Channel performance, isolation characteristics, intrinsic-safety parameters, and HART functionality are determined by the installed modules.
2. Yokogawa-specific system interface
The control-side interface uses a 40-pin Yokogawa system connector. This is a significant compatibility point during replacement. A board with a similar channel count but different Yokogawa connector arrangement is not an electrically safe substitute simply because it is described as an “AI termination board.”
3. HART signal routing
A dedicated 26-pin connector is provided for HART communication. The documented KFD2-STC4-Ex1 configuration supports the HART-capable arrangement, while the KFD2-UT2-Ex1 configuration is specifically identified as having no HART communication. Engineers replacing an existing board should check whether the installed transmitters and DCS configuration actually depend on HART pass-through.
4. Power and alarm supervision
The board uses 24 VDC power and has two 2 A fuse positions associated with the 16-module arrangement. Green power indicators and red fault indicators are shown in the technical drawing. A dedicated alarm connection is also provided, with the documented contact rating of 30 VDC and 1 A.
5. Field wiring matters
Field-side connections are made through screw terminals. For an existing plant, photograph and document the terminal arrangement before removing the original board. Pay particular attention to channel numbering, redundant paths, HART connections, shield/ground treatment, and the relationship between the field terminals and the corresponding Yokogawa I/O channels.
6. Do not confuse the motherboard with an I/O card
This is the most important procurement point. MB-C3- is not a standalone 16-channel AI DCS module. It is the interface/motherboard that accommodates the compatible Pepperl+Fuchs isolators and connects them to the Yokogawa system. Treating it as a direct replacement for an AAI141/AAI143 I/O card would be a category error.
Application Scenarios
- Yokogawa CS3000 analog-input signal interface systems
- Hazardous-area 4–20 mA transmitter interfacing
- 16-channel Pepperl+Fuchs K-System analog-input arrangements
- Yokogawa AAI141 / AAI143 applications
- HART-enabled analog transmitter installations
- Existing DCS termination-panel replacement
- Plant maintenance and legacy control-system spare inventory
Pepperl+Fuchs documentation specifically identifies the board for Yokogawa systems and associates it with AAI141/AAI143 analog-input applications.
Engineer’s Guide: Field Pitfalls
Pitfall 1 — Buying the board without the isolators.
The motherboard does not replace the K-System signal isolators. Confirm which modules are installed in the existing assembly.
Pitfall 2 — Assuming every analog configuration supports HART.
HART depends on the installed isolator and wiring arrangement. KFD2-STC4-Ex1 and KFD2-UT2-Ex1 should not be treated as functionally identical.
Pitfall 3 — Ignoring the Yokogawa connector configuration.
Verify the existing system connector, cable, and I/O card before installation.
Pitfall 4 — Treating 24 VDC as the signal voltage.
The 24 VDC figure refers to the motherboard supply. It does not mean the field analog input signal is a 24 VDC measurement.
Pitfall 5 — Replacing only the visible board.
Before commissioning, verify the complete chain: transmitter → field wiring → isolator → motherboard → Yokogawa cable → DCS I/O card → engineering database.
Frequently Asked Questions
Is MB-C3- an analog input module?
No. It is a Pepperl+Fuchs analog-input termination motherboard designed to accommodate compatible isolator modules.
How many channels does it support?
The board provides 16 module positions and is documented as a 16-channel analog-input motherboard.
Which isolators are associated with this board?
Pepperl+Fuchs documentation identifies KFD2-STC4-Ex1 and KFD2-UT2-Ex1 for the analog-input configuration.
Does it support HART?
Yes, the motherboard provides a dedicated 26-pin HART connection. Actual HART functionality depends on the installed isolator configuration; KFD2-UT2-Ex1 is specifically documented as a no-HART option.
What is the supply voltage?
The documented motherboard supply is 24 VDC.
Is it suitable for a new Yokogawa installation?
It is clearly associated with legacy Yokogawa CS3000 configurations. For a new project, compatibility with the selected Yokogawa I/O architecture and Pepperl+Fuchs interface system should be confirmed rather than assuming this legacy termination design is appropriate.
Procurement Note
For an exact replacement, specify the complete Pepperl+Fuchs MB-C3- (7605) part number. Before purchasing, verify the existing Yokogawa system, 40-pin system cable, installed K-System isolator type, HART requirement, field terminal arrangement, and redundant-channel configuration. The board drawing also identifies the FSY-L640-108873 cable associated with the module positions, so cable and termination compatibility should be checked as part of a replacement project.
