Description
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Product | Reliance Electric WR- |
| Part Number | 843001 |
| System | |
| Product Type | Mother chassis |
| Module Slots | 3 |
| Slot Standard | CompactPCI type |
| PICMG Version | PICMG 2.1 Rev. 3.0 |
| Signal Voltage | 3.3 V |
| Bus Width | 32-bit |
| Bus Frequency | 33 MHz |
| Auxiliary Memory | CompactFlash, PC Card ATA compatible |
| Power Input | 5 V through backplane |
| Power Capacity | 5 V, 4 A |
| Operating Temperature | 0 to 55°C |
| Storage Temperature | -20 to 85°C |
| Dimensions | 65 × 220 × 222 mm without modules |
| Dimensions with Modules | 65 × 220 × 250 mm |
| Weight | 1.718 kg, excluding modules |
The three slots are intended for option modules. The DSP module must occupy the far-right slot, while the PG and SERCOS modules can occupy the other available positions according to the system configuration.
Product Introduction
The Reliance Electric WR- is the mother chassis used in the programmable servo controller. It provides the physical and electrical platform for the controller’s DSP, pulse-generator (PG), and SERCOS modules rather than performing the servo-control processing itself. The chassis mounts into slot 0 of the base unit and provides three CompactPCI-type module positions.
For maintenance teams supporting older motion-control equipment, the WR- matters because a failed chassis or damaged backplane connection can prevent otherwise serviceable controller modules from operating correctly. It should therefore be evaluated as a system-level chassis component, not substituted with an apparently similar CompactPCI enclosure without checking the mechanical and electrical interfaces.
Application Scenarios & Field Pitfalls — The Engineer’s Perspective
Engineering Pain Point
A common problem with legacy motion-control systems is finding that the processor or DSP module tests correctly on the bench, yet the complete controller still fails after installation. With the WR-, the backplane, slot assignment, power delivery, and module seating are part of the control architecture. Replacing only the suspected electronic module may not solve a chassis-level fault.
WR-D4008
Typical Applications
- servo-control systems — provides the chassis platform for the DSP and motion-control option modules.
- Multi-axis motion control — supports configurations using PG modules for encoder feedback and analog outputs.
- SERCOS-based drive systems — provides the mounting position for the SERCOS master module.
- Legacy machine maintenance — useful as a replacement chassis when an existing rack has mechanical, connector, or backplane damage.
The architecture can use up to two PG modules, with each PG module supporting five encoder input channels and five analog outputs, allowing a configured control card to support up to ten axes.
Technical Pitfalls
1. Do not treat WR- as the processor.
The DSP module performs the servo-control processing. The WR- is the mother chassis that houses the modules.
2. Slot position matters.
The DSP module is required in the far-right, slot-3 position. Installing modules in an incorrect arrangement can prevent a configuration from operating as intended.
3. Check the backplane power path.
The chassis receives 5 V from the power card through the backplane, with a specified 5 V/4 A capacity under the stated configuration. A chassis replacement should therefore be evaluated together with the associated power card and backplane connections.
4. Do not confuse it with an I/O module.
Several secondary listings incorrectly describe WR- as an analog-input module, digital I/O card, or standalone PLC processor. The Reliance Electric manual identifies it specifically as the mother chassis, part number 843001.
5. Check the complete module configuration before procurement.
A replacement WR- does not by itself recreate a working controller. The DSP, PG, SERCOS, blank-panel, power, and application-memory configuration must match the existing machine architecture.
Related Products
- Reliance Electric S-D4031 / DSPM-1A — DSP module installed in the WR- chassis; executes the servo-control programs.
- Reliance Electric WR-D4009 / MCIM-1 — PG module providing encoder-related inputs and analog outputs.
- Reliance Electric S-D4039 / SRCS-1 — SERCOS master module for communication with the drive system.
- Reliance Electric MB-D4017 — blank panel used to cover an unused chassis slot.
- Reliance Electric 843705 — part number associated with the DSPM-1A module.
- Reliance Electric 843708 — part number associated with the MCIM-1 PG module.
- Reliance Electric 843709 — part number associated with the SRCS-1 SERCOS module.
- Reliance Electric — complete programmable servo-control platform using the WR- mother chassis.
Procurement Note
For a WR- replacement, verify the 843001 part number, chassis condition, module slots, rear/backplane connectors, and compatibility with the installed module set. If the existing controller is still running, record the DSP, PG, and SERCOS module configuration before removing the chassis. This is especially important on legacy machines where the application software and motion configuration may not be readily available elsewhere.
