Description
The Yokogawa ALP121 is a high-performance PROFIBUS-DP master communication module designed for integration within Yokogawa CENTUM VP distributed control system (DCS) architectures. Operating in field control units (FCU) or node interface units (NIU), the module establishes deterministic, high-speed cyclic data exchange with PROFIBUS-DP slave field devices, motor management systems, and variable frequency drives (VFDs).
Technical Specifications
| Parameter | Value |
| Manufacturer | Yokogawa Electric Corporation |
| Model Code | ALP121 (e.g., ALP121-S00, ALP121-S01) |
| Protocol Support | PROFIBUS-DP Master (DP-V0, DP-V1) |
| Physical Interface | RS-485 via Sub-D 9-pin female connector |
| Transmission Rate | 9.6 kbps to 12 Mbps (auto-detection / configurable) |
| Supported Node Count | Up to 125 PROFIBUS DP slaves (verify topology limits with OEM datasheet) |
| System Compatibility | CENTUM VP / Field Control Units (FFCS / N-IO / FIO environments) |
| Redundancy | Dual-redundant configuration supported via paired modules in adjacent slots |
| Power Consumption | Supplied via node bus; 5 V DC nominal (typically < 800 mA) |
| Operating Temperature | −20°C to +70°C (standard operational limits depend on enclosure ratings) |
| Mounting Type | Direct insertion into field control unit baseplate slots |
Availability and Commercial Terms
- Condition Options: New Original (Factory Sealed), New Surplus, or Refurbished (tested and certified)
- Lead Time: Standard 1 to 3 business days for off-the-shelf surplus; 2 to 4 weeks for factory orders
- Warranty: 12-month standard replacement warranty on all units
- Pricing Note: Price subject to market conditions; contact us for a firm quote.
Engineering and Integration Notes
In field deployments across oil & gas, chemical processing, and power generation facilities, the ALP121 serves as a bridge between high-level CENTUM VP control strategies and lower-level field instrumentation.
- DP-V1 Diagnostics: The module handles DP-V1 acyclic read/write calls, allowing process engineers to execute remote device parameterization, calibration, and HART-over-PROFIBUS pass-through using Yokogawa FieldMate asset management software.
- Redundancy Switching: In dual-redundant setups, active-to-standby switchover occurs without dropping connected PROFIBUS slaves or causing system bus disruptions. Ensure both modules share identical GSD device database files in the system builder database.
- Bus Termination & Shielding: Maintain RS-485 termination resistor settings at both physical endpoints of the segment. Ground the cable shield properly at the cabinet entry point to prevent common-mode noise issues at 12 Mbps baud rates.
Frequently Asked Questions
What is the difference between ALP121-S00 and ALP121-S01 suffixes?
Suffix codes designate specific hardware revision levels, conformal coating options (e.g., protection against corrosive gases per ISA-71.04 Class G3), or temperature range ratings. Always check the physical rating label on the module module housing or consult the OEM datasheet prior to installation in harsh environments.
Does the ALP121 require external power supplies?
No. The ALP121 draws its operating power directly from the backplane of the field control unit or node interface unit. However, external PROFIBUS segment repeaters or active terminators on the field bus loop require independent external 24 V DC power sources.
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