ALF111-S50

The Yokogawa ALF111-S50 is a FOUNDATION Fieldbus communication module designed for Yokogawa N-IO/FIO systems. It provides four fieldbus ports, with each port supporting one segment at a transmission speed of 31.25 kbps. The module supports LAS and clock master functions, dual-redundant configuration, and up to 48 control I/O points per segment under specified scanning conditions.

Communication Functions

The ALF111-S50 interfaces with FOUNDATION Fieldbus devices using the low-speed voltage-mode interface. Its four independent ports support one fieldbus segment per port, allowing multiple field device networks to connect through a single communication module.

• Interface: FOUNDATION Fieldbus, low-speed voltage mode
• Number of ports: 4
• Segment allocation: 1 segment per port
• Transmission speed: 31.25 kbps
• Communication functions: Link Active Scheduler (LAS) and clock master

The maximum device count is 32 units per segment, including the ALF111 module itself. This limit should be considered when calculating the number of field devices connected to each segment.

Control I/O Capacity

The module supports a maximum of 48 control I/O points per segment. High- and medium-speed scanning cycle requirements can be accommodated by specifying up to six I/O points as high-speed scanning types on the ER bus.

The high-speed scanning allocation is therefore configuration-dependent. The number of points assigned to this category must be considered when planning the control I/O configuration.

Bus Connection and Installation

External bus connections use pressure clamp terminals on a removable terminal block. The terminal block incorporates built-in terminators that can be switched on or off, allowing termination settings to be configured at the fieldbus connection.

The module connects to its terminal board through a dedicated cable. Supported installation locations include the following module units:

• ANB10, ANB11
• AFV30, AFV40
• A2FV50, A2FV70

The exact suffix and hardware configuration of the installation unit should be checked against the applicable system configuration.

Redundancy and Electrical Characteristics

The ALF111-S50 supports dual-redundant operation. Two ALF111 modules can be configured in the designated adjacent slots within the same node unit. This arrangement provides a redundant communication module configuration.

The module has a specified withstand voltage of 1500 V AC for one minute. This applies to isolation between the primary and secondary sides and between channels. Its current consumption is 0.5 A or less.

Technical Specifications

Parameter	Specification
Model	ALF111-S50
Base Model	ALF111
Brand	Yokogawa
Product Type	FOUNDATION Fieldbus Communication Module
Application	N-IO/FIO
Interface	FOUNDATION Fieldbus, low-speed voltage mode
Number of Ports	4
Segments	1 segment per port
Transmission Speed	31.25 kbps
Maximum Control I/O	48 points per segment
High-Speed Scanning	Up to 6 I/O points per segment
Maximum Fieldbus Devices	32 units per segment, including ALF111
Communication Functions	LAS function, clock master function
Redundancy	Dual-redundant configuration
Bus Connection	Pressure clamp terminals
Terminal Block	Removable, with built-in switchable terminators
Terminal Board Connection	Dedicated cable
Installation	ANB10, ANB11, AFV30, AFV40, A2FV50, A2FV70
Withstand Voltage	1500 V AC for 1 minute
Current Consumption	0.5 A or less
Weight	0.40 kg

Model and Suffix Identification

The ordering designation ALF111-S50 consists of the ALF111 base model and the specified suffix codes.

Code	Description
ALF111	FOUNDATION Fieldbus Communication Module
-S	Standard type
5	Without explosion protection
0	Basic type

The -S50 configuration identifies the standard, non-explosion-protected, basic version. Explosion protection should not be assumed for this model when selecting equipment for hazardous-area installations.

Frequently Asked Questions

Q: How many FOUNDATION Fieldbus devices can the ALF111-S50 support?

A: The maximum is 32 units per segment, including the ALF111 module itself. Since the module provides four ports with one segment per port, the device limit must be calculated separately for each segment.

Q: Does the ALF111-S50 support redundant operation?

A: Yes. Two ALF111 modules can be installed in the designated adjacent slots of the same node unit to establish a dual-redundant configuration.

Q: Can the ALF111-S50 be used in explosion-protected installations?

A: The suffix code 5 specifies a version without explosion protection. This model should not be treated as an explosion-protected device. Verify the required hazardous-area protection separately when selecting fieldbus communication hardware.

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