1734-AENT setup without Studio 5000: IP address, chassis size, and why it rejects your changes

Somebody buys an old cabinet at auction, finds a POINT I/O rack inside, and tells me they are stuck until they get a Logix Designer license. I hear some version of that every few months. For the adapter itself, it just isn't true.

A 1734-AENT needs exactly two settings before it will carry I/O: an address and a chassis size. Both go in with the thumbwheels, a web browser, or RSLinx Classic Lite, which is free. Studio 5000 only comes into it when a Logix controller has to own the rack. So here is what each tool can set, the thumbwheel codes that catch people, and the protection mode that makes a healthy adapter refuse an IP change.

Two settings live in the adapter, the rest comes from the controller

The adapter keeps its IP configuration and its chassis size in nonvolatile memory, plus a few housekeeping items like the web password and a host name. Module configuration is not in there. Input filters, analog ranges, fault states, all of it sits in the controller project and goes out to the modules when the controller opens its connections.

That's why Rockwell's replacement procedure for this adapter runs sixteen steps, and almost every one of them is unclipping and reclipping hardware. The two that end it are the only real settings: the IP address and the chassis size.

Chassis size is the one the controller never sends. The 1734-AENT will not allow a single I/O connection until the stored number equals the modules on the rail plus one for the adapter itself, and a new or factory-reset unit comes set to one. Meaning the adapter alone.

What an adapter swap keeps, and what has to be set again by hand.

Setting	Stored in	Can be set without Logix Designer
IP address, mask, gateway	Adapter	Thumbwheels (192.168.1.x only), web page, BOOTP-DHCP Tool, EtherNet/IP Address Commissioning Tool, RSLinx Classic
DHCP on or off	Adapter	Web page, BOOTP-DHCP Tool, EtherNet/IP Address Commissioning Tool, RSLinx Classic
Chassis size	Adapter	Thumbwheels (firmware 5.015 or later), web page, RSLinx Classic
Web server on or off, web password	Adapter	Thumbwheels, web page
Module configuration, RPI, keying	Controller project	No. Needs Logix Designer with the adapter's Add-on Profile, or the software for whatever third-party scanner owns the rack

Where each setting lives, and what can change it without Logix Designer.

RSLinx Classic Lite is a free download, and the free edition handles every RSLinx job in that table. It just won't own I/O. For a ControlLogix or CompactLogix to run the rack you need Logix Designer and the adapter's Add-on Profile, and a Series C adapter needs that profile installed before Logix Designer can configure it at all.

A third-party scanner can own a 1734-AENT too, it's a standard EtherNet/IP adapter. You just end up sizing the assembly connections by hand instead of letting a profile do it, and the chassis size still has to be right before any of that works.

Thumbwheel codes, and why 888 makes a good unit look dead

Three digits on the front of the 1734-AENT, each set with a pair of + and - buttons you press with a pen tip. Straight in, light pressure. Rockwell puts the force at about 2 N, so if you're leaning on it, stop.

The adapter reads the wheels at power up, so change them with power off. That isn't just procedure: turning a switch under power can draw an arc, and in a hazardous location an arc is an ignition source.

Wheels set to	What the adapter does at power up
001	IP 192.168.1.1, mask 255.255.255.0, gateway 0.0.0.0
002 to 254	IP 192.168.1.xxx, mask 255.255.255.0, gateway 192.168.1.1
801 to 864	Sets chassis size 1 to 64 (firmware 5.015 or later). Ethernet ports stay off while the wheels sit here
888	Factory reset: DHCP enabled, auto-negotiate on, web server on, web password back to "password". Ethernet ports stay off until the wheels move and power cycles again
000	Turns the web server on. Module Status flashes red to confirm. Then set the address and cycle power again
901	Turns the web server off. Module Status flashes red to confirm. Then set the address and cycle power again
999, or any value not listed	Asks for an address over DHCP if DHCP is enabled, otherwise uses the address stored in memory. New units ship on 999 with DHCP enabled

Thumbwheel settings and what the adapter does with each one.

888 catches more people than every other code put together. Power up on 888 and the adapter wipes its network settings, but it also shuts its Ethernet ports off, which leaves a freshly reset unit looking completely dead. It stays that way until you remove power, set the wheels to something else and power up again. Write down the old setting before you go to 888. You will want it back.

Say you have a Series C adapter and four I/O modules on a bench, and you want the rack at 192.168.1.10. Power off and set 805: four modules, and the adapter counts as the fifth. Power up and watch POINTBus Status: it flashes red at first, then goes solid green once the count matches. Keeps flashing red? The count is wrong or a module has a fault. Power off, set 010, power up. Give the laptop 192.168.1.50 with a 255.255.255.0 mask and the adapter answers at 192.168.1.10. That's two power cycles, and you never opened a program.

Two power cycles, no software: set the count, let POINTBus confirm it, then set the address.

The wheels only ever produce 192.168.1.x addresses. If the plant network is 10.20.30.x, they can't get you there.

Putting a 1734-AENT on any other subnet

Leave the wheels on 999, or any value that isn't an address, and the adapter keeps asking for one over DHCP. Then answer it.

The BOOTP-DHCP Tool ships with RSLinx and with Logix Designer, and Rockwell also offers it as a separate download. Start it and the adapter's MAC address shows up in the request history. The same MAC is printed on a label on the side of the 1734-AENT, which helps when six devices on the wire are all asking at once. Double-click the entry, type the IP, OK. Then pick it in the relation list and press Disable BOOTP/DHCP.

That last button is the whole job. Skip it and the address works fine until the next power cycle, when the adapter throws it away and starts asking again. When somebody tells me an adapter keeps losing its IP, this is nearly always why.

Two more things about the tool. Run it from a laptop with a single connection to that network, not Wi-Fi plus a dock plus a USB adapter, or the tool can simply fail. And the relation is tied to the MAC, which is fixed in the hardware, so a replacement adapter needs a new entry.

Rockwell's newer EtherNet/IP Address Commissioning Tool does the same thing with more room to work. It flips a device between dynamic and static, sets addresses on devices whose MAC you know but whose IP you don't, and takes a spreadsheet list of MAC and IP pairs. On one rack it doesn't matter which tool you pick. On forty, the list import earns its keep.

Once the adapter has any working address, RSLinx Classic Lite finishes the job. RSWho, right-click the adapter, Module Configuration, Port Configuration tab, Manually configure IP settings. That's also where you fix a bad gateway. Keep the gateway inside the adapter's own subnet, or at 0.0.0.0 when there is no router.

And don't leave an I/O adapter on DHCP in production. Rockwell is blunt about this one: dynamic addressing is for initial configuration only. A DHCP server hands out leases, the adapter renews at half the lease time, and nothing guarantees the same address comes back. If a different one does, the controller loses the rack while the machine is running.

What the built-in web pages are good for

From firmware 2.011 on, the web server comes enabled by default. Type the adapter's IP into a browser and log in with admin and password, both case sensitive. On current firmware the adapter makes you change that password at the first login, three wrong tries lock you out for a minute, and ten idle minutes send you back to the login page.

On a used unit, three pages do most of the work.

Identity holds the chassis size, along with host name, description and location. Network is where you pick static or DHCP and enter IP, mask and gateway. Port speed and duplex live there too. Leave them on auto-negotiate unless the switch port is forced, because a duplex mismatch gives you intermittent dropouts that can eat a week. Then there's Browse Chassis, which queries slots 1 through 63 and lists every module the adapter actually sees. I run that before I believe any module is bad.

Nothing on the configuration pages takes effect until the adapter resets or cycles power. People change the IP, see the old address still answering, and decide it didn't save.

Rockwell recommends keeping the web server off when it's not in use, which is what 901 on the wheels is for. 000 brings it back.

Why a working 1734-AENT won't take a new IP

This one looks exactly like a fault. The adapter is in a running rack, a controller owns it, and you try to change the IP from the web page or from RSLinx. It refuses and tells you it's in protected mode.

That's Implicit Protected Mode. It switches on by itself the moment the adapter becomes the target of an I/O connection, or bridges one, and while it's on the adapter will not accept:

·       Ethernet settings such as port speed and duplex

·       a new IP address, subnet mask or DHCP mode

·       a firmware update

·       disabling or re-enabling its ports

·       a remote reset

There is no setting to turn it off. It ends when every I/O connection to the adapter stops. If you have Logix Designer online with the controller, inhibit the adapter in the I/O configuration, make the change, and un-inhibit it. No Logix Designer? Stop the machine, take the adapter off the controller's network and plug the laptop straight into it. Once the connections are gone, the change goes through.

Most people reach for 888 here instead. It works, but it also throws away everything else you had set, and now you're re-addressing a unit that was never broken.

The adapter stops refusing changes once the last I/O connection to it closes.

Swapping an adapter in a rack that was running

Power off before the old 1734-AENT comes out. Pulling or seating an adapter with power applied interrupts the backplane, and that can mean unexpected machine motion. Keep the end cap from the old unit too. It covers the exposed contacts on the last base, and a loose used adapter doesn't always come with one.

Then the two settings. Old adapter ran on thumbwheels? Copy the numbers across. One that got its address over BOOTP needs its relation rebuilt with the new MAC. Chassis size gets set by hand every single time, because nothing else is going to set it.

Keying comes next. With Exact Match in the project, a replacement on a different firmware revision gets its connection refused. Compatible Module lets a newer revision stand in, and that's what most projects I open are set to.

A Series C has a floor of its own: controller firmware 17 or later, RSLogix 5000 version 17 or later, RSLinx 2.56 or later, and the Add-on Profile installed. If the rack talks through a 1756-ENBT, that bridge needs firmware 4.006 or later.

Read the LEDs before you call a 1734-AENT dead

Four status lights on the adapter: Module Status, Network Activity, Network Status and POINTBus Status. Two more on the power side show system and field power. Most adapters I get called about as dead were saying exactly what was wrong through these.

Status lights on the 1734-AENT, top to bottom: Module Status, Network Activity, Network Status, POINTBus Status.

Light	State	What it means	Check first
Module Status	Solid red	Unrecoverable fault: self-test or firmware failure	Replace it. Don't spend the afternoon trying to reflash it
Module Status	Flashing red	Recoverable fault. Also the normal response to 000, 901 or an 8xx setting	Wheel setting, an interrupted firmware update
Module Status	Flashing green	Needs commissioning: configuration missing or incomplete	IP address and chassis size
Network Activity	Off	No Ethernet link	Cable, switch port, the RJ45 jack
Network Status	Off	No IP address	Wheels, DHCP, BOOTP relation
Network Status	Flashing green	Has an IP, no CIP connections	Normal on a bench. On a machine, the controller is not connecting
Network Status	Flashing red	One or more connections timed out	Controller, network path, RPI
Network Status	Solid red	Duplicate IP address	The other device using that address
POINTBus Status	Flashing red	Module count doesn't match chassis size, a module is missing, or a node timed out	Chassis size, module seating, empty bases
POINTBus Status	Solid red	Unrecoverable: the adapter is bus off	Bases and backplane contacts, then the adapter

What each status light is telling you, and where to look first.

Duplicate IP deserves one more line. When the adapter joins a network where something already holds its address, the adapter is the one that backs off. A laptop that grabbed the address first carries on like nothing happened, and the adapter sits there solid red.

Keep empty bases out of the rack entirely, too. The adapter can't detect an empty base, so it can't tell where the modules after it really sit.

Connections that won't open on a busy rack can be the adapter running out of processor. Every connection takes a share, and when there isn't enough left, the 1734-AENT rejects new ones. The Diagnostic Overview page shows CPU utilization, check it there. Rockwell's floor is an RPI of 10 ms for rack-optimized and enhanced rack-optimized connections and 50 ms for direct connections, and plenty of racks I've looked at run tighter than that for no reason anybody remembers.

Questions that come up with this adapter

Do I need Studio 5000 to configure a 1734-AENT?

Not for the adapter. Its address and chassis size can be set from the front panel wheels, from a browser, from the BOOTP-DHCP Tool or from the free RSLinx Classic Lite. Logix Designer, with the Add-on Profile for the adapter, only matters once a ControlLogix or CompactLogix is supposed to run that I/O.

What is the default IP address of a 1734-AENT?

There isn't one. It ships with DHCP enabled and the wheels on 999, so out of the box it waits for a DHCP server. Set the wheels anywhere from 002 to 254 and it comes up at 192.168.1.xxx instead, mask 255.255.255.0, gateway 192.168.1.1.

What is the default username and password for the 1734-AENT web page?

Username admin, password password, both lowercase and case sensitive. Changed it and lost it? An 888 reset restores the default.

How do I reset a 1734-AENT to factory defaults?

Write down the current wheel setting, power off, set 888 and power up. Ethernet stays dead after that first boot, which is normal. Power off again, set the wheels to the address you want or to 999 for DHCP, and power back up.

How many modules can a 1734-AENT support?

Up to 63 I/O modules, but not on its own backplane power. The adapter puts out 1.0 A on the POINTBus, and typical modules use that up long before slot 63. Add up the backplane current of your modules, and once it passes 1.0 A, add a 1734-EP24DC or 1734-EPAC expansion supply. The adapter itself draws up to 1000 mA at 10 to 28 V DC, 10.4 W max at 28.8 V.

If the adapter really is gone

Go through the LED table first. Solid red on Module Status is a dead adapter. Almost everything else on that list is a setting, a cable or an address. When it really is the hardware, we keep the 1734-AENT and the dual-port 1734-AENTR on the shelf as new open-box surplus, both with our 2-year warranty. For a rack that has outgrown the adapter's 1.0 A there is the 1734-EP24DC expansion power supply, plus 1734-TB and 1734-TOP bases for the extra slots. Send us the catalog number and series letter off the old adapter's label and we'll tell you what matches.