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Zonker's Cyclades/Avocent Console Server Connections Guide
(updated: Jul 14, 2011, 09:34 am)

This document will outline terminal server connections to Cyclades TS and ACS series console servers. Most Cyclades devices have a label on the bottom of the case showing the RJ45 signal pinouts, but I've also presented them below. All connections shown here make use of standard ethernet cables (RJ-45, 8-conductor, 'straight through' cables) unless specified otherwise.

Table of Contents
Cyclades RJ-45 signaling
RJ-45 Cable Diagrams
RJ45 to DB/DE adapter wiring diagrams
Specialty cable diagrams
(U.S. Robotics/3Com, Sun-T3, DEC MMJ, ADC Kentrox)
Devices with DE-9(m) console ports
Devices with DB-25(f) console ports
Connecting to Cisco RJ-45 ports
Attaching devices to a PC instead
Connecting modems to Cyclades Products
Terminal Server Configuration Tips
Firmware Upgrade tips
Author Credits

Cyclades RJ-45 signaling

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The table below shows the signal information for the Cyclades 8-wire RJ45 interface used on th TS and ACS console servers. In early 2006, Avocent acquired Cyclades, and Avocent adopted this interface to continue in the Avocent ACS product line.

Patch Panel

Signal Type











Sig. Gnd.















Cyclades Loopback schematic
Male RJ45 pinouts
Female RJ45 pinouts

1) Input means a signal from the external device, coming in to the RJ-45 port
2) Output means a signal source from the RJ-45 port, going out to the external device

Cable Diagrams

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Ethernet cable schematic

Cyclades p/n CAB0018
APACN part: 24490-21

USOC Rolled cable schematic

APACN part: 24490-22

Crossover Ethernet schematic

Standard Ethernet cables follow a specific wiring pattern. However, not ALL ethernet cables have 8 wires in the cable, since a standard Ethernet interface only uses 4 of the wires. For console connections, you need to make sure that your cables have all 8 wires, either 'straight through' (as shown to the left) for most connections, or 'rolled' (as shown in the center). The USOC cable used for CDDI connections will not work as a "null-modem" cable, since the Cyclades/Avocent wiring schema is not symmetrical.

The Crossover Ethernet cable will not work as a null-modem cable for Cyclades gear.

Cyclades RJ-45 Adapter Schematics

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Cyclades and Avocent provide a few adapters with each console server. Cyclades used to also make some cable diagrams available on their website. Most of the diagrams here are my own work, and some were confirmed with the Cyclades site. In keeping with my guide style, I'm providing diagrams for a large matrix of adapters and cables. Where there is an existing Cyclades/Avocent part number, it will be noted with the schematic.

I am a strong proponent of buying pre-wired, pre-labeled adapters and cables. Generally speaking, you probably can't build an adapter cheaper, if you consider the value of your time as well as the component costs. Whether or not I can make 100 adapters without a mistake isn't being questioned, but I'm sure I'd rather not make, label and test 100 adapters by myself. The best advantages for buying pre-built adapters and pre-wired cables include;

Check my "where to buy" page for vendor information.

With all of this said, I also understand that sometimes you just need to make that one cable or adapter, and buying just one isn't practical. So, here are the schematics. The Cyclades part number, when available is shown below each adapter. (ADB = a modular adapter with a female RJ45 connection; CAB = a 3' "silver-satin" cable with an RJ45 male connection.)

YFDCE schematic

Cyclades p/n ADB0017

YFDTE schematic

YMDCE schematic

Cyclades p/n ADB0025

YMDTE schematic

YFDCE91 schematic

YFDTE91 schematic

YMDCE91 schematic

YMDTE91 schematic

YFDCE92 schematic

Cyclades p/n ADB0036

YFDTE92 schematic

Cyclades p/n ADB0200


Cyclades p/n ADB0037

YMDTE92 schematic

Specialty Cables for Cyclades Console Servers

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As with adapters, I recommend buying pre-built, pre-labeled, tested cables. If you need to make them yourself, make sure you label each end, since the cables are NOT symmetrical! It's important to get the ends connected to the correct equipment.

The cables below will help you connect the Cyclades port to other console server devices.

Cyclades to Cyclades schematic

Cyclades p/n CAB0046
Cyclades to Cisco Console schematic

Cyclades p/n ADB0039

Cyclades to Lantronix, Cisco Patch Panel

Cyclades to Cisco CSS11500

Cyclades to Digi CM schematic

Cyclades to Opengear CM schematic
Cyclades to Micro Annex schematic
Cyclades to Xyplex, iTouch, MRV schematic

Cyclades to ServerTech CDU

Cyclades to Computone RAS
Cyclades to EIA-560 schematic
Cyclades to EIA-561 schematic

U.S. Robotics (USR, now 3-Com) digital modem chassis have a different pinouts than Cyclades on the console ports on their NICs and NACs.

You can also make a single cable, with RJ-45 male connectors on each end. Make sure that you label both ends of the cable, since the wiring is not symmetrical (it makes a difference which end plugs into the Cyclades port!) 

Cyclades to 
      USR schematic

There are more cables listed on the Cyclades Host-to-Adapters Page.

Sun T3 ('Dilbert') Storage Shelf Hardware

The Sun Netra T-3 disk arrays use an RJ-13 connector for it's RS-232 console, and you only get data and ground for your connection (no flow control or handshaking).

Cyclades to Sun T3 schematic
Male RJ45 pinouts

There are more cables listed on the Cyclades Host-to-Adapters Page.

Digital Equipment Corp. (DEC, then Compaq, then H.P.) equipment often used an RJ-13 with an offset locking tab, referred to as a Modified Modular jack (MMJ). This included their VT-series terminals, VAX equipment, and even newer Alpha series equipment.

Cyclades to DEC MMJ

There are other cables listed on the Cyclades Host-to-Adapters Page.

ADC Kentrox Some ADC Kentrox equipment has a different RJ45 wiring schema on the console ports on their equipment. Make sure that you label both ends of the cable, since the wiring is not symmetrical (it makes a difference which end plugs into the Cyclades port!) 

Cyclades to ADC Kentrox schematic

There are more cables listed on the Cyclades Host-to-Adapters Page.

Devices with DE-9 console ports

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Cyclades (now Avocent) makes three DE-9 adapters (they call them 'connectors') and one cable, although only two of the adapters come with each new ACS unit.

  • (1) ADB0036 - female RJ45 to female DE-9, grey hood (I call this YFDCE92)
  • (1) ADB0200 - female RJ45 to female DE-9, black hood (I call this YFDTE92)

The grey ADB0036 plugs into a 'normal' 9-pin PC serial port, allowing the Cyclades to exchange data with the PC.

Cyclades to Device

In addition to these first two adapters, the other DE9 offerings from Cyclades have been;

I use the CAB0036 to connect my laptop to new ACS units on my bench, for the pre-configuration process.

Rather than list all of the connection possibilities on this page, I have created my Cyclades Host-to-Adapters Page, which lists which adapter (or cable) you will need to connect any device on the list to a Cyclades/Avocent TS or ACS port.

Note: Some Cisco 1900-series switches use a DE-9M DTE console connection, instead of the Cisco-wired RJ-45 connector. Some of these devices with DE-9M ports do not want to see the DCD signal on the connection, while other versions of the 1900 will require this signal. (If the Cisco 1900 you have attached a DE-9 adapter to is spewing AT modem commands out the port, you've got the wrong adapter. If you picked a YFDCE92, then use the YFDCE91.) 

The YFD*E91 series adapters do not have the DCD connection tied to DSR, while the YFD*E92 series do have the tie connecting DSR to DCD on the DE-9.

Devices with DB-25 console ports

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Cyclades provides a DB-25F cable (CAB0017), a DB-25M adapter (ADB0025) and a DB-25F Loopback adapter with all new ACS units. While you can use the ADB0025 adapter with the DB-25F loopback adapter, this is a bulky and heavy combination. If you have a spare female RJ45 connector, you can make a small, lightweight loopback adapter by making three connections (pin 1 to pin 5, pin 2 to pin 8, and pin 3 to pin 6).

Cyclades to Device wiring

For many years, Sun used the female DB25 connector for their TTY A and B ports. If you have older Sun gear, the CAB0025 (cable) or ADB0025 (adapter) are what you will need to conenct those TTY ports to a Cyclades ACS or TS console server port.

Rather than list all of the connection possibilities on this page, I have created my Cyclades Host-to-Adapters Page, which lists which adapter (or cable) you will need to connect any device on the list to a Cyclades/Avocent TS or ACS port.

For basic RS-232 troubleshooting info, view my Minor Scroll of Console Knowledge

Cisco devices with RJ-45(f) console ports

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Cyclades to Sun Netra cabling

Many vendors have adopted the wiring scheme used by Cisco Systems, including Sun (Nertra and SunFire product lines, among others), Juniper Networks, and ADC CMTS, Enterasys Dragons, Nokia VPN Gateways, Server Technology PC. Logical Solutions console servers also use this wiring scheme, but they can set their ports to either DTE or DCE modes. (In DTE mode, the Logical Solutions devices look like a Cisco console port.)

When connecting a Cycldes terminal server to Cisco-wiring-scheme devices, the best method is to use a straight-through 8-wire cable, such as a CAT-5 Ethernet cable between the Cyclades console server port and the female end of the ADB0039 "Cyclades to Cisco/Sun" in-line RJ45 adapter. The male end of the ADB0039 adapter then plugs into the Cisco-scheme port. (Yes, an 8-wire CAT-3 cable would work fine, if you can still find them.)

Lantronix SCS console servers use the null-modem opposite wiring of the Cisco port. You would need to put a USOC-rolled cable between the Cyclades ADB0039 adapter and the Lantronics ports.

The connection will not work if you put the ADB0039 adapter on the Cyclades end of the cable. The adapter needs to go on the Cisco-device end of the cable.

Rather than list all of the possibilities here, I have created a Cyclades Host-to-Adapters Page, which lists the various combinations of devices which use the Cisco RJ45, and other DB25 and DE9 connector types. The list also tells you which adapter (or cable) you will need to connect each device to a Cyclades console server port.

Attaching devices to a PC for configuration

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Connecting Cyclades adapters to a Laptop

When you are deploying console servers, you may still want to have a way to wheel a terminal or a laptop up to a machine to check configurations (basically, the practical (or paranoid) among us want to have a safety net, in case the console services fail). In this case, using modular adapters actually simplifies our job!

By connecting all of your remote consoles to console server ports using Ethernet cables, all you need to do to use your laptop for easy configuration is to connect an YFDCE91 (ADB0200) adapter to your laptop, and set up a Terminal Emulator package to talk to the serial port of the laptop. (You can use the Cyclades Host-to-Adapters Page to determine which adapter (or cable) you will need to connect any device on the list to a Cyclades/Avocent TS or ACS port, if you don't already have the correct adapter or cable attached.) Use an Ethernet cable to connect the adapter on the laptop to the adapter on the device that you want to configure.

If you want to set up a "crash cart", I'd also suggest that you set the serial port speed on all of your consoles to 9600 bps, 8-N-1 (since is the most common setting). Having a common speed removes one more variable to have to remember during a crisis.

If you have any Sun workstations connected to your console services, you should test to make sure that your terminal emulator software doesn't send a serial BREAK when you start/stop it, since the BREAK signal will likely send your Sun host to the OK prompt. (This has also been reported on some SGI and NeXT hosts.)

When you have successfully configured your device(s) with the laptop, all you need to do is disconnect the cable coming from the adapter on your PC, and reconnect the cable coming from the console server to restore the connection to the console server.

Connecting modems to Cyclades Products

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You can connect a "stand-alone" modem to almost any device. (Your modem configuration may be affected by the signals available on the Cyclades device port, i.e. the state of the flow control and hardware handshaking signals.) The ACS series units can also support using PCMCIA modem cards. Attach the YMMOD adapter to the female DB-25 connector on most modems, and use an appropriate length of ethernet cable (and another adapter on the host-side, as needed), as indicated in the illustrations below.

console server to modem

This section is, unfortunately, a bit vague, due to a few problems related to modem connections;

  1. The slim variety of connectors used on console ports on Cyclades gear (DE9, DB25)
    1. Some console server ports may not care if DSR is toggled, but that's how the modem will signal whether a call is on the line, in the configurations shown below.
  2. The settings for the various devices, to talk to the modem
    1. Some consoles may need to be configured to understand that there is a modem on the console
    2. You should probably put an IDLE timeout on these console (or aux) ports, to hang-up after a period of inactivity, since these are your consoles!
    3. While you *may* be able to configure some ports to allow SLIP or PPP, you probably don't want that in most instances. You may need to invoke certain commands to prevent that possibility on some devices.
  3. The modem settings required to make whichever modem you choose work.
    1. I like the USR/3-Com Courier modems if you are connecting to these ports so you can dial into them. (Personally, I'd avoid the USR Sportster in this case! They are OK for outbound dialing, but unreliable as in inbound modem, in my opinion. Feel free to ask me why in email.)
    2. You may need to modify the settings so that DCD reflects the state of the phone connection, since the MMOD connector ties the DSR pin of the adapter to the DCD signal of the modem.

As a result, configuration, for the most part, is left as an exercise for the reader (or it can be a topic for a discussion on consulting rates ;-).

If you use the Cyclades PCMCIA modem, the configuration is pretty simple, versus setting up an external modem. This is proably the best way to connect a modem to the Cyclades units.

Configuration Suggestions for Cyclades Console Servers

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Tips for configuring the serial ports on terminal servers for remote access to attached serial devices.

  • Choose which line(s) will be used for connecting devices.
  • Don't run a login session on the port. (it'll only chat with the attached device)
  • Don't set the port for local login. (this will cause the port to issue a login when it sees the connection. It will time out, and disconnect you. Conserver will re-initialize the port, but this will fill your logs...)
  • Set the port to allow Reverse Telnet.
  • Set the port speed, data bits, parity, and stop-bits (most folks use 9600-8-N-1)
    • (there are arguments for setting the port speeds higher.)
  • Decide if you want/need software or hardware flow control.

You can use the example below to get started.

        all.protocol socket_server
        all.socket_port 7001+
        all.break_sequence ~break
        all.issue \r\n\
        Welcome to terminal server %h port S%p \n\
        all.prompt %h login:
        all.term vt100
        all.speed 9600
        all.datasize 8
        all.stopbits 1
        all.parity none
        all.lf_suppress 1

If you are connecting your network equipment consoles to your console server, remember to consider;

The variables used in the configs and scripts are as follows;

Cyclades Firmware Upgrade tips

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I've upgraded many TS and ACS units. This section will attempt to cover what I've learned along the way, and to point out the important details I've discovered (some of which weren't pointed out in BOLD ALL-CAPS PRINT, but probably should have been).

  1. Read the Cyclades upgrade notes when you can find them! Follow the instructions you find in the notes to the letter, if you have any trouble making them work. I've found that the micro-Linux they used doesn't always allow you to make shortcuts that you might expect to be able to do in a full-blown Linux.
  2. Once you know a process is working, THEN you can experiment with it. The original Cyclades "README" files have not let me down. But, the older docs have not been updated. The old notes talk about using FTP to move files around, but you can also use SCP on newer versions. I discovered this later on in my experience, so I don't knw how early you can try SCP (for example), I'll offer you some tricks to help you, but if the tricks are not working for you, refer to rule #1 above!
  3. You can NOT just upgrade an old machine to the latest code! Depending on which old version you are running, you may need to upgrade through four seperate versions

TS Pre-Upgrade Clues: Before you try to upgrade, you should check how much RAM you have installed. (Some versions of firmware will require that you have certain amounts as a minimum...and you will render your console server unusable if you try to load one of those newer version is you have too little RAM installed! The Cyclades upgrade notes will remind you of this, but I'm putting the clues here as well.)

Login as root, and type "cat /proc/meminfo" (Look at MemTotal entry...).

  •     If you have a TS1000, MemTotal should be 32 MB or more
  •     If you have aTS2000, MemTotal should be 64 MB or more
  •     (If MemTotal is LESS than listed for the firmware revision you desire, then DO NOT UPGRADE!)

If you want to add a Message Of The Day, you can edit the /etc/motd file. However, this is NOT normally saved to flash! If you want the message to persist across resets and power failures, you will need to add this file in /etc/config_files.txt. I usually add it just below the SSH config file information. (It doesn't matter where you put it, but it's easier to check if you put it in a consistent place on all of your console servers.)

One possible use of the MOTD is to display a "private system, authorized users only" message upon login, similar to the example below;

=====        PERMISSION IS PROHIBITED       =====
=====            AND IS MONITORED           =====
=====                                       =====
=====  ***********************************  =====
=====      [ company name here ]            =====
=====      [ street address optional ]      =====
=====      [ city is also optional ]        =====
=====  ***********************************  =====
=====      [ device name ] [ location ]     =====

Even if the banner doesn't convince an intruder to log off, you can convince the jury that you were trying to warn the intruder prior to them causing any problems.

Best Practice: Backing up your ACS config

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This process will NOT work for the TS units.

If you should have a hardware failure, and need to send your ACS unit in for repair, you may not get that same unit back. The repair department may opt to send you a different machine back, or you may need to press a new (replacement) unit into service, and you may ned to configure this "new" unit with the same accounts and settings as the previous unit.

Fortunately, the ACS makes this task easy, because the saveconf command collects everything you need into a single G-ZIP'd file. You should make an effort to move a copy of this file to another server for safekeeping. You can do this manually, or using a cron job under the root account (if you have a file server which will alays be waiting for the transfer.

The files in this ZIP file include the password and grup info, home directories, the pslave.conf file, and many configuration files. (The entire list is controlled by the /etc/config-files file, which is on the list. You can also add files to the list...I add a Message of the Day (/etc/motd/) to my devices.)

If you have a pre-shared SSH key from your console server to your fileserver, you can use SCP to move the file /proc/flash/config.tgz to your fileserver. (Your script should give it a name that relates to the hostname of the console server, as well as the current date/time, in case you are backing up more than one units config file. Your script should also be entered into the /etc/config-files file, along with your pre-shared key, so that you will have them on the NEW console server, when you configure it by using a copy of this ZIP file.)

When you move the file back into an ACS, you will need to rename it during the transfer to be /proc/flash/config.tgz, so the unit will recognize it when you boot.

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