ABB Bailey IEMMU21 Rear-Mount Module Mounting Unit – 12-Slot Harmony Rack
ABB Bailey IEMMU21 rear-mount module
12-slot Harmony rack mounting unit
ABB PLC rear-mount module unit
Brand Name:
ABB
Model Number:
IEMMU21
ABB Bailey IEMMU21 rear-mount module
,12-slot Harmony rack mounting unit
,ABB PLC rear-mount module unit
ABB Harmony Rack Hardware
IEMMU21 Rear-Mount Module Mounting Unit
A 12-slot Harmony rack chassis that carries controller, communication and I/O modules while routing Controlway, the I/O expander bus and regulated logic power.
Product Introduction
IEMMU21 is a rear-mount module mounting unit for ABB Bailey Harmony rack hardware. It provides a 12-slot card chassis and a backplane that distributes Controlway, the I/O expander bus and regulated logic power to installed controller, communication and I/O modules.
ABB identifies the 21 version as the rear-mount chassis without primary AC/DC power distribution. It is therefore not a power supply and power modules must not be installed in it.
Technical Specifications
| Part number | IEMMU21 |
|---|---|
| Product type | Rear-mount module mounting unit |
| System role | Mechanical mounting, backplane communication and regulated logic-power distribution for Harmony rack modules |
| Capacity | 12 rack modules |
| Cabinet mounting | Standard 483 mm (19 in.) cabinet |
| Dimensions | 483 × 178 × 304 mm (19 × 7 × 12.2 in.) |
| Weight | 3.63 kg (8.0 lb) |
| Distributed buses | Controlway and I/O expander bus |
| Regulated module voltages | +5 VDC, +15 VDC and −15 VDC |
| Operating cabinet temperature | 0 to 70 °C (32 to 158 °F) |
| Operating humidity | 5–95% to 55 °C; 5–45% to 70 °C, noncondensing |
| Storage / transport temperature | −40 to 85 °C (−40 to 185 °F) |
| Storage / transport humidity | 0–95%, noncondensing |
| Air quality | Noncorrosive |
Compatibility & Replacement
ABB documents IEMMU11, IEMMU12, IEMMU21 and IEMMU22 as functional equivalents for earlier IEMMU01 and IEMMU02 mounting units. The physical cabinet orientation and primary-power requirement still determine the correct version: IEMMU21 is rear mounted and has no primary-power distribution.
A mixed installation with an older IEMMU01 or IEMMU02 requires the documented transition board. The newer units use a grey I/O expander-bus ribbon cable; the older units use an amber cable. Do not treat a chassis-only swap as cable-compatible without checking the interconnect.
Backplane, Bus Segmentation & Installation
Confirm rear access, no distributed primary power, module count and cabinet rail spacing.
Follow plant lockout procedures before work on the system power bus or backplane.
Apply the manual's Controlway segmentation, dipshunt and jumper instructions for the installed module set.
Check the grey expander-bus cable, logic-power connections and module seating before restart.
ABB states that the backplane can divide Controlway into three segments. Segment configuration is application-specific and should follow the installed controller/interface instruction, not a generic jumper setting.
Applications & Fault Scenarios
Rack renewal
Used when a damaged rear-mount card chassis or backplane must be replaced while retaining compatible Harmony rack modules.
Communication faults
Intermittent Controlway or I/O expander-bus errors can point to loose ribbon cables, incorrect segmentation, connector damage or an incompatible older interconnect.
Logic-power loss
Multiple modules dropping together can indicate a mounting-unit power connection or backplane problem rather than simultaneous module failures.
Mechanical damage
Bent guides, damaged captive-latch points or a distorted chassis can prevent full connector engagement and create repeat faults after module replacement.
Cooling restriction
The open top and bottom support cabinet airflow. Blockage, debris or poor module spacing raises the risk of temperature-related instability.
Migration mismatch
Replacing IEMMU01/02 without the required transition hardware can interrupt the expander bus and prolong commissioning.
Official Documentation
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ABB — Harmony Rack I/O Product OverviewWBPEEUS240011B1Open official manufacturer source
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ABB — Harmony Rack Communications OverviewWBPEEUS250002C1Open official manufacturer source
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ABB — Harmony Power Supply Upgrade Kit — MPS III3BUS095388 Rev AOpen official manufacturer source
Amikon Service
The service terms below are Amikon commercial support and are separate from ABB technical documentation.
Inspection & testing
Incoming identity and condition checks; functional or power checks are applied where the part and available fixture allow. The agreed scope can be stated on the quotation.
Packaging & DOA
Protective industrial packing appropriate to the item. Report any dead-on-arrival issue promptly with label, package and installation evidence.
Returns, warranty & support
Returns require prior RMA approval and condition review. Warranty term and coverage are confirmed on the quotation; after-sales support assists with claim evidence and part verification.
Multi-brand Spare Parts Also Requested
These part numbers are independent purchasing references only. They are not replacements for the product on this page. Compatibility and stock must be confirmed separately for each item.
FAQ
What is the cabinet role of ABB IEMMU21?
It provides the rear-mounted 12-slot card chassis, backplane buses and regulated logic-power distribution for compatible Harmony rack modules.
Can power modules be installed in ABB IEMMU21?
No. The manufacturer identifies this version as having no primary-power distribution and states that power modules are not installed in it.
Can ABB IEMMU21 replace an older IEMMU01 or IEMMU02?
ABB calls the newer mounting units functional equivalents, but the cabinet orientation and interconnect hardware still matter. Mixed or migrated installations require the documented transition arrangement.
What must be checked when connecting ABB IEMMU21 to an older mounting unit?
Check the transition board and cable type. The newer expander-bus interconnect is grey; the older IEMMU01/02 cable is amber.
How is Controlway configured on ABB IEMMU21?
The backplane can be segmented, but the exact jumper and dipshunt setup depends on the installed controller and interface modules. Use the applicable ABB module and MMU instructions.
What should be included in an ABB IEMMU21 RFQ?
Send the part number, quantity, destination, required date, machine/system model, cabinet orientation and details of any older MMU that must remain connected.
RFQ for IEMMU21
For a faster technical and commercial check, send the installed-part details before the requested ship date.
Email Miya Zheng- Part Number
- Quantity
- Destination
- Required Date
- Machine / System Model
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