Q Series Communication Module Selection: QJ71E71 vs QJ61BT11N

By Abdullah Zahid
19 min read
Mitsubishi Electric QJ71E71 Ethernet module and QJ61BT11N CC-Link module installed in MELSEC-Q base unit rack

MELSEC-Q QJ71E71 vs QJ61BT11N Module Comparison: Choosing the Right Q Series Communication Architecture

Controls engineers specifying a MELSEC-Q system often face the same fork in the road: does this application need the Q Series Ethernet Interface Module QJ71E71, the Q Series CC-Link Master/Local Module QJ61BT11N, or both? These are not interchangeable parts. The QJ71E71 connects the Q Series CPU to programming PCs, SCADA systems, HMIs, and IT infrastructure over TCP/IP and UDP/IP on 10BASE-T Ethernet. The QJ61BT11N connects that same CPU to CC-Link remote I/O, inverters, and distributed intelligent devices over a deterministic CC-Link fieldbus. Getting this choice wrong at the design stage costs real time during commissioning — and sometimes means adding a second module mid-project.

If you have already confirmed which module fits your architecture, check current pricing and availability for MELSEC-Q communication modules at LeadTime.ca — ships worldwide.

QJ71E71 or QJ61BT11N: Which One Does Your Q Series System Actually Need?

This comparison is right for MELSEC-Q project engineers who are mapping their communication architecture before finalizing the BOM. Use the criteria below to position your application:

  • Your primary connectivity targets are SCADA servers, engineering PCs, HMIs, historians, MES, or ERP systems — QJ71E71 is the natural starting point
  • Your field layer includes CC-Link remote I/O racks, CC-Link-compatible inverters, or other CC-Link devices — QJ61BT11N anchors that network
  • You require deterministic, cyclic I/O refresh across distributed panels — CC-Link via QJ61BT11N is the appropriate choice
  • You need vendor-neutral remote diagnostics, VPN access, or standard Ethernet protocol support — QJ71E71 provides that path
  • You are extending an existing CC-Link installed base — QJ61BT11N maintains that infrastructure with minimal disruption
  • Your plant serves both IT-level integration and distributed CC-Link devices — most medium and large Q Series systems need both modules simultaneously

If your application has no CC-Link devices and requires only Ethernet connectivity, QJ61BT11N adds unnecessary complexity. Conversely, if your entire field layer depends on CC-Link I/O and drives, QJ71E71 alone cannot serve that role. The honest answer for the majority of real-world Q Series installations is that both modules belong in the rack.

On this page:

What Each Module Actually Does in a MELSEC-Q System

Mitsubishi documentation identifies the QJ71E71 as an Ethernet interface module for MELSEC-Q, supporting communications based on TCP/IP and UDP/IP over 10BASE-T Ethernet. Its job is to give the Q Series CPU a window into the broader IT and OT world — connecting to programming software running on engineering PCs, SCADA platforms, HMI panels, peer controllers, and data infrastructure. Communication methods include MELSEC protocols and MC protocol, making it compatible with a wide range of third-party SCADA and HMI packages that include Mitsubishi Ethernet drivers. The QJ71E71 installs in a standard Q Series base unit slot and draws power through the backplane like any other Q Series module.

The QJ61BT11N is a fundamentally different class of module. Mitsubishi documentation identifies it as a CC-Link master/local module for MELSEC-Q, used to connect the CPU to CC-Link remote I/O and other CC-Link devices. Where the QJ71E71 faces outward toward IP networks and IT systems, the QJ61BT11N faces downward into the machine and process layer — linking to remote I/O racks, CC-Link-compatible inverters, distributed intelligent devices, and other CC-Link nodes. It supports operation as either a CC-Link master or a local station. Like the QJ71E71, it occupies one slot in a Q Series base unit and is powered from the backplane. The core distinction is that these two modules operate at different levels of the automation hierarchy, not as competing options for the same task.

A note on Ethernet module variants: Mitsubishi technical notes confirm that the QJ71E71-100 outperforms the QJ71E71 on 10BASE-T networks and is recommended as an upgrade option for new or replacement applications. This article compares the QJ71E71 and QJ61BT11N as the principal communication options, but engineers specifying a new system should verify whether the QJ71E71-100 is the preferred current Ethernet module for their configuration before finalizing the BOM.

Where These Modules Sit in a Typical Q Series Signal Chain

Both modules plug into the MELSEC-Q base unit alongside the CPU, but they connect to entirely different downstream worlds. Understanding that separation is the fastest route to making the right selection.

  • Q Series CPU in base unit — shares backplane with both communication modules, accessing each through its internal bus
  • QJ71E71 faces upward and outward — Ethernet switch connects it to engineering PCs, SCADA servers, HMI panels on the plant LAN, and potentially to MES or cloud gateways
  • QJ61BT11N faces downward into the field — CC-Link bus cable runs in daisy-chain topology to remote I/O stations, CC-Link inverters, distributed panels, and intelligent devices
  • In a combined architecture, the two modules coexist in the same rack: CC-Link for deterministic real-time control at the device layer, Ethernet for supervision and data integration above it
  • Engineering software running on a PC connects to the CPU via the QJ71E71 Ethernet path; CC-Link device configuration is downloaded to QJ61BT11N via the same engineering tools but through the PLC programming connection

Ethernet vs CC-Link: Real-Time Behavior and Control Determinism

The most important performance distinction between these two modules is not raw throughput — it is determinism. The QJ61BT11N operates as a CC-Link master delivering cyclic, deterministic I/O refresh across the fieldbus. The CC-Link protocol is designed for time-critical machine-level control, and its cycle-based behavior means that remote I/O states update on a predictable schedule. This makes QJ61BT11N the appropriate choice when distributed panels must respond reliably within tight scan-time constraints, such as motion-adjacent I/O or safety-critical interlocks managed through the fieldbus layer.

The QJ71E71, by contrast, operates over standard Ethernet, which is inherently non-deterministic. Ethernet performance depends heavily on network design — the quality of switches, network loading, VLAN segmentation, and contention from other devices sharing the same infrastructure. For SCADA, data logging, HMI updates, and programming access, this non-determinism is acceptable and usually invisible. For time-critical distributed I/O, pushing all remote nodes over a standard Ethernet network without careful design and hardware selection introduces jitter and inconsistent update times that are difficult to diagnose. The practical rule is straightforward: use CC-Link via QJ61BT11N when your field layer requires deterministic I/O refresh, and use Ethernet via QJ71E71 when your requirement is supervisory communication, data exchange, or engineering access.

Network Topology and Integration Paths for Each Module

The QJ71E71 uses a star topology built around standard Ethernet switches. IP addressing, subnet configuration, and port assignments are set through Mitsubishi engineering software network parameters. This architecture reuses IT infrastructure already present in most plants — patch panels, managed switches, and structured cabling — and the module's compatibility with MC protocol makes it straightforward to connect third-party SCADA and HMI platforms that include a Mitsubishi Ethernet driver. The main integration challenges tend to come from the IT side: firewall rules, VLAN boundaries, and IP addressing conflicts with existing plant networks. Coordinating with IT early in the project prevents the majority of these issues.

The QJ61BT11N uses CC-Link bus topology, where the master and all stations share a single shielded cable running in a daisy-chain configuration with terminators at each end. Station numbers, baud rate, and network parameters are configured through the same Mitsubishi engineering software, but the workflow is different from Ethernet configuration. CC-Link has specific cabling requirements — cable type, maximum segment lengths that depend on the configured baud rate, proper shielding and grounding — and errors in these areas are the most common source of intermittent CC-Link faults in the field. When those rules are followed, the QJ61BT11N delivers stable, reliable fieldbus performance in industrial environments. The payoff for the additional setup discipline is a deterministic device network that integrates directly with CC-Link remote I/O, drives, and intelligent devices without requiring additional gateways.

A mixed architecture using both modules in the same Q Series rack is the standard approach for medium to large systems. CC-Link via QJ61BT11N handles the device layer; Ethernet via QJ71E71 handles supervision, programming, and plant network integration. Keeping these two networks segmented — CC-Link on its own dedicated bus, Ethernet on its own switch segment — simplifies troubleshooting and prevents traffic from one network affecting the other.

Five Decision Scenarios: When to Choose QJ71E71, QJ61BT11N, or Both

The following scenarios map directly to the most common application situations for MELSEC-Q communication module selection. Each has a clear recommendation grounded in the architectural logic above.

Scenario 1 — Small machine with a single HMI and no remote I/O: The only connectivity needs are engineering PC access and one Ethernet HMI, possibly with plant network data logging. There are no distributed I/O panels. In this case, QJ71E71 is the right and sufficient choice. CC-Link adds no value without CC-Link devices, and keeping the architecture simple reduces commissioning time.

Scenario 2 — Medium machine with distributed I/O and CC-Link inverters: The application requires deterministic control of multiple remote I/O nodes and CC-Link-compatible drives, with SCADA either local or accessed via a gateway. QJ61BT11N anchors the CC-Link field layer. If SCADA or remote engineering access is also required, QJ71E71 should be added — but CC-Link comes first in this architecture.

Scenario 3 — Existing plant with a substantial CC-Link installed base: A new Q Series CPU must integrate into an established CC-Link network with many existing devices. Reusing that infrastructure with QJ61BT11N is the least disruptive path. If the existing system already has a separate Ethernet path for SCADA, QJ71E71 can be added; otherwise, CC-Link alone may be sufficient depending on the SCADA architecture.

Scenario 4 — Data-centric application with MES or cloud integration: The primary requirement is frequent data exchange with databases, MES systems, or cloud platforms. Local I/O in the same cabinet does not require a fieldbus. QJ71E71 is the correct module. CC-Link provides no benefit in this scenario without CC-Link field devices, and Ethernet is the natural path to IT-level integration via standard protocols and gateways.

Scenario 5 — Large production line with both SCADA and a wide CC-Link I/O and drive footprint: The system needs reliable fieldbus for many remote I/O stations and CC-Link-connected drives, plus central SCADA, historian access, and remote engineering connectivity. This is the scenario where both QJ61BT11N and QJ71E71 together are the correct answer. CC-Link provides deterministic fieldbus for the device layer; Ethernet provides plant network integration and supervisory access. Attempting to force either module to serve both roles introduces architectural compromises that create ongoing maintenance problems.

Side-by-Side Specification and Role Comparison

Feature QJ71E71 (Ethernet) QJ61BT11N (CC-Link) Comparison Note
Network type Ethernet (TCP/IP, UDP/IP, MELSEC protocols) over 10BASE-T CC-Link fieldbus (master/local station) Different network layers and use cases — not direct alternatives
Typical role PLC interface to programming PCs, SCADA, HMIs, IT systems, peer controllers Fieldbus master/local for remote I/O, inverters, CC-Link intelligent devices Ethernet is supervisory/peer; CC-Link is field-level control
Topology Star via Ethernet switches Bus-type CC-Link network with terminators Impacts cable routing and field wiring design
Determinism Non-deterministic; depends on Ethernet design and loading Deterministic, cycle-based CC-Link behavior CC-Link favored for strict real-time distributed I/O
SCADA/HMI connectivity Direct connection over Ethernet — native advantage SCADA typically connects via Ethernet or gateways, not directly on CC-Link QJ71E71 advantage for SCADA and supervisory systems
Remote I/O network Requires Ethernet-based remote I/O solutions and additional hardware Native CC-Link remote I/O support QJ61BT11N advantage for CC-Link distributed I/O
Programming access Direct support for programming and monitoring via engineering PCs Typically not used as primary engineering link QJ71E71 advantage for engineering tools
Cabling Standard Ethernet twisted-pair CC-Link-specified shielded cable and terminators CC-Link cabling rules are more specific and must be followed closely
Slot and power usage One Q Series slot, powered from base unit backplane One Q Series slot, powered from base unit backplane Neutral — both consume rack resources equivalently
Engineering complexity Familiar to IT/OT teams; firewall and VLAN issues can arise Specialized fieldbus knowledge required; CC-Link cabling discipline critical Scenario-dependent based on available site expertise

Full technical specifications are available on the product page at LeadTime.ca.

Factor QJ71E71 QJ61BT11N Context
Module cost tier Similar class communication module Similar class communication module Exact pricing varies — verify with distributor before quoting
Associated hardware Ethernet switches, patch cords, possible routers or firewalls CC-Link shielded cable, terminators, CC-Link I/O and devices Total system cost depends heavily on device count and distances
Ecosystem cost Wide range of Ethernet HMIs and SCADA at various price points CC-Link I/O and drives can be cost-effective when many nodes share one bus Evaluate entire system cost, not module cost in isolation
Availability Often widely stocked where Ethernet-based automation is common Common in Mitsubishi-centric plants; may be more specialized inventory Market-typical estimate — verify with distributor before quoting

If your architecture calls for both modules, confirm current availability and lead times for QJ71E71 and QJ61BT11N together at LeadTime.ca before finalizing your BOM.

Expert Verdict: How Experienced Q Series Engineers Choose Between These Modules

The QJ71E71 is the right module when the question is how the Q Series CPU talks to the world above it: SCADA platforms, engineering PCs, HMI panels, historians, MES, and IT-level data infrastructure. Its 10BASE-T Ethernet interface, TCP/IP and UDP/IP support, and compatibility with MC protocol make it the practical first choice for any application where the primary communication targets are IP-addressed systems. If your plant already runs standard Ethernet infrastructure and your tools support Mitsubishi Ethernet drivers, the QJ71E71 integrates into that environment with manageable engineering effort. The buyer who should prioritize this module is the engineer connecting a Q Series CPU to a SCADA system, enabling remote programming access, or building a data path to an MES or cloud platform — with no CC-Link field devices in the device list.

The QJ61BT11N is the right module when the question is how the CPU talks to the layer below it: CC-Link remote I/O racks, CC-Link-compatible drives, distributed intelligent panels, and any third-party equipment with a native CC-Link interface. Its deterministic, cycle-based fieldbus behavior is what makes it the correct answer for applications where I/O update timing matters, distributed panels are spread across a machine or line, and the device inventory is CC-Link-centric. Where engineers sometimes go wrong is expecting the QJ61BT11N to also serve as a SCADA gateway or a general-purpose plant network interface. It does neither efficiently. If SCADA is also required in a CC-Link-centric architecture, the answer is not to force SCADA over CC-Link — the answer is to add QJ71E71 alongside QJ61BT11N. Mitsubishi technical notes also confirm that QJ71E71-100 is the recommended Ethernet module upgrade option for new applications, so engineers designing from scratch should verify which variant is current before ordering.

The procurement reality is that both modules remain active in the MELSEC-Q product family and are used together in the majority of medium to large real-world installations. Lead time and stock levels for MELSEC-Q communication modules can vary depending on region and current demand, making it worth confirming availability before committing to a build schedule. LeadTime.ca sources MELSEC-Q modules globally and can help identify in-stock options, confirm lead times for both QJ71E71 and QJ61BT11N, and advise on newer Ethernet variants where architecture permits — check current availability at LeadTime.ca before your BOM is locked.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide. Contact LeadTime.ca here.

What Engineers in the Field Say About These Modules

Community discussion about the QJ71E71 on forums including Reddit r/PLC and PLCTalk reflects a module that does its job reliably when the network is set up correctly. Practitioners consistently praise it for straightforward SCADA and HMI connectivity once IP addressing and MC protocol settings are configured. The issues that surface in community threads are almost never hardware defects — they are configuration problems, typically around MC protocol frame format selection, port assignments, and the behavior of unmanaged switches or IT-side firewalls. A recurring field tip is to align with the plant IT team early in the project to agree on IP ranges, VLAN placement, and firewall rules before the panel ships, rather than discovering those conflicts during commissioning.

The QJ61BT11N draws consistent praise in practitioner discussions for stable, deterministic operation in industrial environments — particularly in automotive and manufacturing plants where CC-Link is the established fieldbus standard. Engineers who have worked with it in well-wired installations describe it as a reliable, low-maintenance backbone for distributed I/O and drives. The complaints that appear most frequently center on the learning curve for engineers who are new to CC-Link: station numbering logic, parameter download procedures, and the strict cabling requirements that include specific cable type, shielding practice, and termination at both ends of the bus. Intermittent CC-Link faults in the field are traced overwhelmingly to mis-termination or poor shielding rather than to module failures, and the corrective action is almost always a wiring inspection rather than a module replacement.

The most consistent message across community discussions about QJ71E71 vs QJ61BT11N is that experienced practitioners stopped treating them as competing options long ago. The architecture that works — and that comes up repeatedly in forum threads about medium to large Q Series systems — is CC-Link via QJ61BT11N for the device layer, Ethernet via QJ71E71 for supervision and remote access. Engineers who arrive at a project having already decided to use only one module typically end up adding the other during commissioning when they discover that one network cannot efficiently serve both roles.

Installation and Wiring Overview

All wiring and module installation must be performed de-energized under lockout/tagout by qualified personnel in accordance with Mitsubishi Electric manuals and applicable local electrical codes. The following points summarize what to verify before and during installation:

  • QJ71E71 uses standard Ethernet twisted-pair cabling connected to an Ethernet switch; verify IP address, subnet mask, and port settings in Mitsubishi engineering software network parameters before powering up
  • QJ61BT11N uses CC-Link-specified shielded cable in a bus topology; terminators must be installed at both physical ends of the bus, and cable type, shielding, and grounding must comply with CC-Link specifications — poor practice here is the primary cause of intermittent faults
  • Both modules install in standard Q Series base unit slots and receive power from the backplane; verify that adding communication modules does not exceed the base unit power budget
  • CC-Link station numbers must be unique across the network and must match the parameter configuration downloaded from GX Developer or GX Works2/3; confirm station numbering before energizing the CC-Link bus
  • For QJ71E71, coordinate IP addressing with plant IT before installation to avoid address conflicts, and test basic Ethernet connectivity with a ping before deploying SCADA or MC protocol communications

Engineers requiring full wiring diagrams and step-by-step commissioning procedures should refer directly to the official Mitsubishi Electric module manuals.

Accessories and System Expansion Considerations

Selecting the right supporting hardware for each module is as important as the module selection itself. The following accessories and expansion considerations apply to QJ71E71 and QJ61BT11N deployments:

  • QJ71E71 — Industrial-grade managed Ethernet switches for panel use; Ethernet patch cords rated for the installation environment; surge protection on Ethernet ports for panels in electrically noisy areas; routers or firewall appliances if the Ethernet segment connects to a corporate or IT network
  • QJ61BT11N — CC-Link-specified shielded cable (cable type selection depends on configured baud rate and segment length — consult the CC-Link cabling manual); terminating resistors for both ends of the CC-Link bus; CC-Link compatible remote I/O units, inverters, and intelligent devices from the verified CC-Link device catalog
  • When both modules are installed in the same Q Series rack, plan slot assignments and verify that the combined module count and types do not exceed CPU or base unit limits for the specific Q Series configuration in use
  • For new Ethernet deployments, confirm with Mitsubishi or your distributor whether QJ71E71-100 is the preferred current variant — Mitsubishi technical notes identify it as an improvement over QJ71E71 on 10BASE-T networks and recommend it for new or replacement applications
  • Future-proofing note: plant standards are moving toward Ethernet-based architectures at all levels; when specifying CC-Link infrastructure today, document the CC-Link topology in a way that supports a future transition to Ethernet-based remote I/O without requiring a complete PLC redesign

Common Selection Mistakes — and How to Avoid Them

The following checklist covers the selection errors that appear most frequently in MELSEC-Q communication module projects. Review each point before finalizing your module selection:

  1. Treating QJ71E71 and QJ61BT11N as direct substitutes — assuming you can simply pick one communication module without considering network role. Impact: the system cannot connect to required devices, whether CC-Link I/O or Ethernet SCADA. Prevention: start by listing all devices and networks the PLC must communicate with, then map each to Ethernet or CC-Link.
  2. Expecting CC-Link via QJ61BT11N to replace Ethernet for SCADA or remote engineering access — planning for SCADA or remote PCs to connect directly on CC-Link. Impact: complex or impractical SCADA connectivity; need for additional gateways discovered late in the project. Prevention: plan Ethernet via QJ71E71 or a current Ethernet equivalent for SCADA and engineering access wherever practical.
  3. Relying on Ethernet via QJ71E71 for time-critical distributed I/O without a network design review — pushing all remote I/O over generic Ethernet without addressing determinism and network loading. Impact: inconsistent I/O update times, jitter, and intermittent faults that are difficult to trace. Prevention: use CC-Link or another deterministic fieldbus for time-critical distributed I/O, or design the Ethernet network with appropriate hardware and QoS if an Ethernet-based real-time solution is required.
  4. Ignoring the installed base and maintenance skills available at site — choosing CC-Link or Ethernet purely on technology preference without accounting for existing cabling, spare modules, and staff experience. Impact: higher training burden, commissioning effort, and troubleshooting difficulty. Prevention: factor in plant standards, existing networks, and available skills alongside technical requirements.
  5. Underestimating the cabling and topology impact — deciding on CC-Link versus Ethernet without considering actual cable routes, panel space, and field junction box locations. Impact: unexpected material and labor costs; reliability issues from cabling installed outside specification. Prevention: involve electrical designers early, compare bus versus star wiring for the actual physical layout and distances before finalizing the architecture.

If you are unsure which module or combination is right for your specific Q Series configuration, the LeadTime.ca team can assist with module identification and sourcing. Contact LeadTime.ca to discuss your application.

Frequently Asked Questions

Can I install both QJ71E71 and QJ61BT11N in the same Q Series rack at the same time?

Yes. Both modules install in standard Q Series base unit slots and are powered from the backplane independently. Running both in the same rack is the standard architecture for medium to large Q Series systems that need CC-Link for the device layer and Ethernet for SCADA, programming, and plant network integration. Verify that the total module count and combined power draw do not exceed the limits of your specific base unit and power supply configuration.

Can QJ71E71 communicate directly with CC-Link devices?

No. The QJ71E71 is an Ethernet module and does not have a CC-Link interface. It cannot connect directly to CC-Link remote I/O, CC-Link drives, or any device that requires a CC-Link master connection. If your field layer includes CC-Link devices, QJ61BT11N is required for that network. The QJ71E71 and QJ61BT11N operate on separate physical networks and serve separate roles.

Is QJ61BT11N a practical choice for SCADA connectivity?

Not as a direct SCADA interface. SCADA systems typically connect to the Q Series CPU over Ethernet using MC protocol or similar Ethernet-based drivers. Connecting a SCADA platform directly to a CC-Link network via QJ61BT11N requires gateways or additional hardware, adding complexity and potential points of failure. For SCADA connectivity, QJ71E71 is the appropriate module. In a combined architecture, QJ61BT11N handles field devices while QJ71E71 carries the SCADA connection.

What happens to the rest of the system if the QJ71E71 Ethernet network goes down?

If the Ethernet network carried by QJ71E71 is lost, SCADA visibility, remote engineering access, and any data logging over Ethernet are interrupted. The CC-Link fieldbus running on QJ61BT11N continues operating independently — remote I/O and drives on the CC-Link network are not affected by an Ethernet failure unless the Q Series CPU itself is configured to halt on communication errors. The separation of these networks is one of the architectural advantages of running both modules.

How do I know whether my devices need CC-Link or Ethernet?

Check the communication interface specifications for each device in your system design. Devices such as remote I/O racks, inverters, and distributed intelligent terminals that carry a CC-Link specification require a CC-Link master — QJ61BT11N. Devices such as SCADA servers, engineering PCs, standard HMI panels, historians, and MES systems that communicate over TCP/IP require an Ethernet interface — QJ71E71. Many real-world device lists include both types, which is why most medium and large Q Series architectures use both modules.

Should I specify QJ71E71 or QJ71E71-100 for a new project?

Mitsubishi technical notes identify the QJ71E71-100 as an improvement over the QJ71E71 on 10BASE-T networks and recommend it as the preferred option for new or replacement Ethernet applications. The same Ethernet versus CC-Link selection logic described in this article applies regardless of which Ethernet module variant is chosen. Verify with your distributor or Mitsubishi representative which variant is currently recommended and available for your specific project before finalizing the BOM.

Why Order From LeadTime.ca

  • LeadTime.ca ships MELSEC-Q communication modules worldwide — not limited to any single region or country
  • Specialist sourcing for hard-to-find or low-stock Q Series modules, including both QJ71E71 and QJ61BT11N
  • Pricing available directly on the product page; contact the team for volume pricing or to confirm lead times before committing to a build schedule
  • Application support for module selection questions — particularly useful when specifying mixed Ethernet and CC-Link architectures or evaluating newer Ethernet module variants
  • Fast response for procurement teams working against project deadlines in automotive, manufacturing, packaging, and process industries worldwide

At-a-Glance Comparison Summary

  • QJ71E71 is an Ethernet interface module for MELSEC-Q supporting TCP/IP and UDP/IP over 10BASE-T — its role is supervisory and IT-level connectivity
  • QJ61BT11N is a CC-Link master/local module for MELSEC-Q — its role is deterministic fieldbus control of remote I/O, inverters, and CC-Link devices
  • Both modules install in standard Q Series base unit slots and are powered from the backplane
  • QJ71E71 uses star topology via Ethernet switches; QJ61BT11N uses CC-Link bus topology with shielded cable and terminators
  • CC-Link via QJ61BT11N is deterministic and cycle-based — correct for time-critical distributed I/O; Ethernet via QJ71E71 is non-deterministic — correct for supervision and data integration
  • The most common architecture for medium and large Q Series systems is both modules together: QJ61BT11N for the device layer, QJ71E71 for plant network and SCADA
  • Mitsubishi technical notes identify QJ71E71-100 as the recommended upgrade option for Ethernet on new or replacement applications — verify the preferred variant before ordering
  • The primary selection question is: which devices must the Q Series CPU communicate with — Ethernet-based, CC-Link-based, or both?
  • Current pricing and availability for both modules can be confirmed at LeadTime.ca, which ships worldwide

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