Mitsubishi / CC-Link, CC-Link IE and MELSECNET

CC-Link and CC-Link IE are different networks that share a name. One runs on shielded twisted pair, the other on Ethernet cable. And CC-Link IE running on Ethernet cable is not Ethernet: an ordinary office switch degrades it.

Mitsubishi networking is where most CC-Link and MELSECNET enquiries come from in New Zealand, usually on imported packaging and process machinery that has been extended over the years.

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The network families

Establish which one you have before anything else, because the modules do not cross over.

The IE in CC-Link IE stands for the Ethernet-based generation. Plain CC-Link is the older twisted pair network and it is still extremely common, because it works and nobody replaces a working network.

A CC-Link module and a CC-Link IE module are not alternatives. Different network, different cable, different configuration.

Master, local and remote

The role decides the part, and on Mitsubishi the role is often one character.

On the FX range the trailing M is the master. An FX3U-16CCL-M is a CC-Link master and an FX3U-64CCL is a slave. One character, and they sit at opposite ends of the network.

On the Q range the module number changes instead, and a QJ71 module is master or local where a QJ72 is a remote station.

Q series network modules

The optical and coaxial trap

The most expensive single mistake on this range.

QJ71LP21-25 is optical fibre and QJ71BR11 is coaxial. Both are MELSECNET/H, both sit in the same rack slot, and both are configured the same way in software.

They are not interchangeable, because the cable in the plant is one or the other. There is no adapter.

Look at what is plugged into the front. Two fibre connectors means LP; a single coaxial connector means BR. Send a photo of the module face if you are unsure, and it settles in seconds.

QJ71 against QJ72

QJ71 modules go in a rack with a CPU. QJ72 modules go in a remote rack with no CPU.

So a QJ72LP25 is the head of a remote I/O drop, taking its instructions from a master elsewhere. Ordering one to fix a remote drop is right; ordering one to add a drop to a system with no master is not.

iQ-R network modules

The R prefix is iQ-R and the Q prefix is Q series. The functions map across but the modules do not fit each other's racks.

The exception is an RQ extension base, which lets Q series modules run on an iQ-R system. That is the staged migration path, covered on our Q series page.

FX series network modules

Note the ENET-ADP is a left-side adapter, not a right-side block. That distinction runs through the whole FX range and is explained on our FX page.

CC-Link remote I/O

The blocks that hang off a CC-Link network, and where most of the volume sits.

Screw terminal against connector is a wiring decision

An AJ65SBTB lands field wiring on screw terminals. An AJ65VBTCU uses connectors. Same network, same function, entirely different termination.

So they are not substitutes on an existing machine. The connector types were chosen at build time and the loom matches one or the other.

Tell us which the existing block is, or send a photo of the front, and we will match it.

AJ65 against NZ2GF

AJ65 is CC-Link and NZ2GF is CC-Link IE Field. Different networks. An NZ2GF block will not join a CC-Link network and an AJ65 block will not join a CC-Link IE network.

Check what the master module is before ordering remote I/O.

The CC-Link cable and terminator problem

The most useful troubleshooting content on this page, because the symptoms are intermittent and get blamed on hardware.

Terminating resistors are not optional

A CC-Link network needs a terminating resistor at each end of the trunk, and the value is matched to the cable type in use.

This is a very common finding on a network that has been extended or had a station removed. Somebody reconnected the trunk and the terminator ended up in the wrong place, or came off entirely.

It costs nothing to check and it is not a hardware fault.

Cable versions matter

CC-Link specifies dedicated cable, and there are version generations of it. Mixing cable versions on one trunk, or substituting ordinary shielded twisted pair, reduces the reliable distance and the achievable speed.

A network that works at low baud and fails when someone raises the speed is usually a cable problem, not a module problem.

The same applies to the total trunk length and the drop lengths, which are both limited and both get exceeded quietly as a machine is extended.

Station numbers and occupied stations

Worth knowing before adding anything to a working network.

Each CC-Link device occupies one or more station numbers, depending on how much data it exchanges. A 64-point I/O block occupies more than an 8-point one.

So a like-for-like replacement is safe and an upgrade may not be. Tell us what you are adding and to what, and we will flag it.

CC-Link IE runs on Ethernet cable and is not Ethernet

The point that catches IT-minded people and costs a day.

CC-Link IE Field uses standard Ethernet cable and connectors, and a deterministic token-passing protocol on top. It is not TCP/IP traffic that a switch can treat as ordinary data.

The failure is not clean. The network often comes up and then suffers timing errors and station dropouts under load, which sends people looking at modules and cables.

Mitsubishi supplies compatible switches in the NZ2EHG range for exactly this reason.

Same class of trap as putting a switch into an EtherCAT line, covered on our Beckhoff junctions page. Ethernet cable and RJ45 connectors do not mean Ethernet rules apply.

Star and line topology

CC-Link IE Field supports line, star and ring topologies. A line topology needs no switch at all, because devices daisy chain through two ports.

So if a machine has no switch and the network works, nothing is missing. And if someone adds a switch to a working line topology, that is where to look when it stops behaving.

Where the configuration lives

So a network module is a straightforward spare, and a remote I/O block needs its station number set.

That second point is where a swap goes wrong. Note the switch settings on the old block before it comes off the wall, or photograph them.

Before ordering a replacement

What to send us

The full module number. It carries the network and the role.

Which network it sits on. CC-Link, CC-Link IE Field, CC-Link IE Control, MELSECNET/H or Ethernet.

What the master module is, if you are ordering remote I/O.

Screw terminal or connector, on an AJ65 block.

Optical or coaxial, on MELSECNET/H. A photo of the module face settles it.

What you are adding and to what, for the station count.

A photo of the rack and of the remote blocks. Mitsubishi labels the front clearly.

What we can supply

Current production. iQ-R RJ71 network modules, CC-Link IE Field remote I/O in the NZ2GF range, NZ2EHG compatible switches, and CC-Link IE TSN hardware. Quoted with a delivered lead time.

Discontinued and mature. QJ61BT11N, QJ71GF11-T2, QJ71GP21-SX, QJ71LP21-25, QJ71BR11, QJ71E71-100, QJ72 remote heads, AJ65 and AJ65SBTB remote I/O, FX2N and FX3U CC-Link and PROFIBUS modules. Surplus and tested used.

Cable, connectors and terminators. The small parts that are usually the actual fault.

Network modules are good spares

Worth stating, because it is not true of every part of a Mitsubishi system.

The network parameters live in the PLC project, so a like-for-like module goes in and works. No laptop, no configuration session.

The one thing to hold alongside them is a set of terminators and a length of the correct CC-Link cable. Both are cheap and both are what fixes the faults people order modules for.

We buy Mitsubishi network hardware

CC-Link and MELSECNET modules hold real value, because a plant still running the network cannot get them new and a like-for-like part avoids touching a working system.

Keep remote I/O blocks with their connectors, and keep terminators and dedicated cable. The accessories are worth more than people expect. See Sell To Us.

Common questions

Can you get a part that is not listed on your site?
Usually. The site shows what we hold, not what we can source.

Is CC-Link IE just CC-Link on Ethernet?
No. Different network entirely, and the modules do not cross over.

Can I use an ordinary switch on CC-Link IE?
No. It needs a compatible switch, or a line topology with no switch at all.

Is a QJ71LP21 the same as a QJ71BR11?
No. One is optical fibre and one is coaxial. Same network, different cable.

Why do my far stations keep dropping out?
Check the terminating resistors before anything else. It is the most common cause and it costs nothing to look.

Do you supply used equipment?
Yes, where new is not available, tested and clearly described.

What is the lead time?
Ex stock items ship the next working day within New Zealand. We give you a firm lead time with the quote.

Do you quote in NZD?
Yes, in NZD including GST for New Zealand customers.

Related

Mitsubishi overview, MELSEC Q series, MELSEC FX, GOT terminals and MELSERVO MR-J.

For industrial networking from other brands see Siemens SCALANCE, Allen-Bradley Stratix, Schneider ConneXium, Phoenix Contact Factoryline and Beckhoff junctions and switches.

Send us your part numbers

Tell us which network the part sits on. And if stations are dropping out, check the terminators before ordering anything. Quotes in NZD including GST.

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Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with Mitsubishi Electric. MELSEC, MELSECNET, MELSERVO, GOT, GX Works and iQ-R are trademarks of Mitsubishi Electric Corporation. CC-Link, CC-Link IE and CC-Link IE TSN are managed by the CC-Link Partner Association. PROFIBUS is a trademark of PROFIBUS Nutzerorganisation. All trademarks, brand names and part numbers are the property of their respective owners and are used here for identification purposes only.