Issue
Alternatives to the FOI1 and FOI2 product which is discontinued and possible replacement using the Westermo ODW-730-F2
Environment
Site using a Fiber Optic Interface on LAN (CLAN) or SCU Network (SubLAN)
Cause
Discontinuation of the FOI1 and FOI2 products which have been available for a number of years.
Resolution
The ODW appears to provide a very cost effective and versatile fiber optic interface for RS485 networks. The ODW is one of only a few RS485/Fiber interfaces that provide the redundant fiber network capability.
Some notable features on the ODW-730-F2 include –
-Dual Fiber Bus Configuration or Dual Fiber Redundant Ring Configuration
-Local status contact output indicates fiber fault detection
-LED indication of Local fiber fault condition (FL L)
CH1 and CH2 LEDs indicate if failure is on incoming or outgoing fiber
-LED indication of Remote fiber fault condition (FL R)
Here the LED indicates when there a fault anywhere in the system.
A summary of controller status points monitoring the Local fault detection would be reviewed to identify location of a fault. Current system operation is probably operating on the basis of the redundant ring. A second fiber fault will disable the ring system. In a bus configuration, you currently have lost some portion of the system communications.
-Supports Asynchronous (SubLAN) and Synchronous (CLAN) protocols
In the case of the synchronous CLAN interface, it is not reconstructing RS485 data quality. Any accumulated distortion on the copper cable segment is passed on to the data through the fiber and will arrive at the other fiber drops in the same condition, although amplitude will be replenished. You must insure you do not exceed copper cable distances and maintain compliance with recommended grade of cable while avoiding stubs and the distortion they produce.
-Alternate Fiber Interface Options are supported two receptacles for plug-in fiber transceiver module purchased separately
The lowest cost and most common interface is the MLC2. Each of the ODWs in this evaluation were configured with 2 of the MLC2 modules
- MLC2 Multimode 62.5/125um or 50/125um 2km Fiber Length
- SLC20 Singlemode 9/125um 20km Fiber Length
- SLC120 Singlemode 9/125um 120km Fiber Length
The ODW also supports the option of bidirectional fiber interface modules. These are more expensive options and currently used infrequently and are not discussed/evaluated here.
-Powered by 24VAC (48-62hz), or 12 to 48VDC (supporting redundant DC)
Power input is isolated from RS485 and Status port signals
-RS485 port is isolated from power AND local ground
The RS485 will take on the ground reference of the incoming RS485 signals. An oscilloscope examination of the RS485 data pins with no connection to other RS485 devices will show AC voltage on the RS485 pins (leakage to isolated circuit). A scope should only be examined with the RS485 port connected to the CLAN or SubLAN.
Please find the attached pdf ODW FOI EVAL 120824.pdf for review. It proceeds through a sequence of differing configurations with the synchronous controller LAN and the asynchronous SubLAN.
