5069-OB16 flashing red: what each light means and the four faults behind it

A lot of the calls I get about a 5069-OB16 start the same way. All sixteen outputs flashing red, module light green, nothing disconnected. Is the card dead? Usually it isn't.

A flashing point on a 5069-OB16 only ever means one of four faults. Work out which one and you know where the meter goes. Here's how I read the lights, in the order I check them.

Two kinds of light on a 5069-OB16

The faceplate has one MOD indicator, green or red, and sixteen point indicators, yellow or red, one per output. They don't watch the same thing. MOD is about the module itself and its connection to the controller. The point lights cover the field side: the output, its load, the power feeding it.

So a green MOD with red points is the good version of bad news. The card is talking to the controller just fine and the problem is out in the wiring. A flashing MOD is a different conversation, usually configuration or the connection, and the field wiring can wait.

What the indicators on a 5069-OB16 mean

Indicator	State	What it means	What I do
MOD	Off	No module power	Check the MOD supply and that the module is seated
MOD	Steady green	Connected to the owner controller, running normally	Nothing
MOD	Flashing green	No connection. Configuration missing, incomplete or wrong	Open the module in Studio 5000 and see what blocks the connection
MOD	Flashing red	Firmware update running or failed, a recoverable fault, or the connection timed out	Check the Connection and Module Info pages, then Reset Module or cycle power
MOD	Steady red	Nonrecoverable fault	Cycle power once. Still red, replace the module
Point	Off	Output off, or no module power	Nothing
Point	Steady yellow	Output on	Nothing
Point	Flashing red	No Load, short circuit, thermal shutoff or field power loss	See the next table

 

A flashing red MOD from a connection timeout isn't always the card's fault either. On a remote rack, a bad cable to the adapter does it just as well.

The four faults behind a flashing point

Each one shows up in the point's tags, so if you're online the tags settle it. If you're not, timing gives it away. Watch when the point flashes: with the output off, with it on, or no matter what.

Telling the four faults apart

Fault	When the point flashes	Tag set to 1	How I prove it	Fix
No Load	Output off for 250 ms or more and the load draws under 0.5 mA. Only if the diagnostic is enabled	I.Ptxx.NoLoad	Command the point on. Flashing stops, yellow comes on	Reconnect the load, or uncheck Enable No Load Diagnostic on spares
Short circuit	Output on for 250 ms or more into more current than it can handle	I.Ptxx.ShortCircuit	Lift the field wire. The point restarts in its commanded state	Find the short, check the load against 0.5 A
Thermal shutoff	Output on, channel overheated by too much load current	I.Ptxx.ShortCircuit (same bit)	Clears once the load is fixed	Lighter load, or an interposing relay
Field power loss	All 16 points at once, on or off. Series B only	I.Ptxx.FieldPowerOff on every point	Meter LA+ to LA- at the seated RTB	Restore LA. Outputs restart on their own

 

No Load gets misread more than the other three. It's disabled by default, so nobody expects it, and then somebody checks Enable No Load Diagnostic on the Points page for all sixteen, spares included. Now every unused point on that 5069-OB16 blinks red the whole time it's off. Nothing's broken. Uncheck it on the spares, or put something on them.

Short circuit and thermal shutoff share one tag, I.Ptxx.ShortCircuit. Thermal is the slow version of the same story: too much current heats the channel until it shuts itself off. A short or overload isn't flagged until the output has been on for 250 ms, so a point that only blips into a short may never flash at all. Inrush has its own limit, 1 A for 10 ms per point, repeatable every 2 s. Big coils and lamps past that belong on an interposing relay. And once the fault clears, the output just restarts in whatever state the program commands. No reset.

All sixteen at once is almost never sixteen bad loads. It's field power. A Series B 5069-OB16 watches LA+ and LA-, and when that supply drops every point faults, every output turns off and FieldPowerOff goes to 1 across the board. Bring it back and anything the program has commanded on turns on again about 100 ms later, by itself. Full recovery can take up to another second past the Output Error Latch Time, so a little lag is normal.

One case I still can't explain. Clean 24 V right on the LA terminals, config checks out, all sixteen keep flashing. I power everything down, MOD and LA both, reseat the card and the RTB, and power up again. If it still flashes after that, I swap it. Haven't found a smarter test for that one.

My five-minute check before anyone pulls a 5069-OB16

1.    Look at MOD first. Steady green means the controller side is fine and you're chasing a field problem. Flashing green or any red on MOD, deal with that before you touch wiring.

2.    Count the red points. On a Series B card, all sixteen together points at LA power, unless No Load is enabled on points with nothing wired. One or two, look at their loads.

3.    Meter LA+ to LA- at the RTB with the RTB seated, not at the power supply. You want 10 to 32 V DC. A blown fuse or a tripped breaker in between never shows up at the supply terminals.

4.    Toggle a flashing point from the program, if the machine lets you do that safely. Red only while it's off means No Load. If it only goes red while on, that's a short or thermal. Red either way, back to step 3.

5.    Go online and read that point's tags. NoLoad, ShortCircuit, FieldPowerOff: whichever one is set is your answer.

Only then does the card come out, and with the power off. Neither the module nor its RTB supports removal or insertion under power.

The 5069-OB16 decision path: MOD first, then how many points are red, then when they flash.

LA power, not SA: what actually feeds the outputs

A 5069-OB16 takes no current from the SA bus at all. Its outputs run on whatever you land on LA+ and LA-, the last two terminals on the 18-pin RTB, right below OUT15. Loads return to the minus side of that same supply.

I've watched people meter SA, find it healthy and condemn the card. SA can be perfect while the outputs have nothing to switch. The card still has to sit on a DC SA bus, though, which is a rack-layout question I went through in the 5069-FPD article.

LA takes 10 to 32 V DC, 24 V nominal, and the module can pass up to 8 A total, 0.5 A per point. I like it on its own fused branch, separate from MOD. A field wiring fault then takes out the outputs and not the controller along with them.

Feeding LA through an E-stop

Plenty of panels switch LA with an E-stop or a safety relay contact, so one button kills all sixteen outputs. That works. Just know what it looks like on a Series B card: every press flashes all sixteen points red and sets Fault and FieldPowerOff on each one. Alarm logic watching those bits will fire every single time somebody hits the button.

The part that matters more is the reset. When LA comes back, every output the program is still commanding on turns back on. The card doesn't hold anything off for you. If that's not what you want, the logic has to drop those commands while LA is gone. Whether a restart like that is acceptable on your machine is a risk assessment call, not the card's.

LA+ and LA- are the bottom two terminals, right below OUT15. Anything that opens the LA feed, an E-stop included, reads as a field power fault on Series B.

Why your meter reads 24 V on an output that's off

This one doesn't flash anything, but it sends people down the wrong road just the same. Put a meter between an off output and LA- with nothing else connected, and you can read close to full supply voltage. That's leakage, under 0.5 mA per point, and a high-impedance meter happily turns it into a big number.

The off-state spec is 5 V DC maximum, but only with at least 1 mA of load on the point. No load, no spec. Where leakage actually hurts is a high-impedance input on the other end, a drive's digital input or another PLC card, that reads it as ON. The fix is a loading resistor in parallel with the load: 5.6 kΩ, 0.5 W at 24 V DC. That pulls roughly 4.3 mA, well past the 1 mA the spec asks for. If a point still reads over 5 V with that resistor across it, then I start doubting the channel.

Same off output, two readings. With 5.6 kΩ across the load, the leakage has somewhere to go.

Series B, the OB16K and the OB16F

Field power loss detection exists on Series B hardware only. A Series A 5069-OB16 has none, lose LA and it raises no field power fault, the outputs just go quiet. That's why a Series B spare dropped in for an old Series A card can start flashing on day one. Usually it's not defective. It's reporting that LA drops out every time something upstream opens, which the old card never bothered to tell anyone.

	5069-OB16	5069-OB16K	5069-OB16F
Outputs	16, sourcing, one group	16, sourcing, one group	16, sourcing, one group
LA voltage	10-32 V DC	10-32 V DC	10-32 V DC
Output current	0.5 A per point, 8 A per module	0.5 A per point, 8 A per module	0.5 A per point, 8 A per module
Output delay	100 µs max	100 µs max	10 µs
Minimum pulse width	200 µs	200 µs	20 µs
Scheduled outputs	No	No	Yes, ±10 µs accuracy
Conformal coating	No	Yes	No
Point diagnostics	No Load, short circuit, thermal; field power loss on Series B	Same	Same
MOD current / SA draw	75 mA / none	75 mA / none	75 mA / none

 

Wiring is identical across all three. Keying isn't. The project stores the catalog number, series and firmware revision for each module, and with Compatible Module keying the installed card needs the same catalog number and the same or a higher major revision. So an OB16K going into an OB16 slot means changing the module in the project first. A card with older firmware than the project expects won't connect, and the controller logs a keying fault. Inhibit the module, flash it to the right revision, uninhibit. Firmware only from Rockwell, never from a third-party site.

Checking a used 5069-OB16 on the bench

Wherever it came from, this takes about ten minutes. Read the label for catalog number and series first. Then put the card on a controller or adapter with an end cap, MOD power and a 24 V supply on LA, configure it, and wait for a steady green MOD.

Turn on No Load for all sixteen points with nothing wired. Every point should flash red while it's off, which proves each channel's indicator and diagnostics in one go. Then hang a load on each point, a 5.6 kΩ resistor is enough, and toggle it. On, the point goes yellow and the voltage across the load sits within 0.2 V of LA. Off, it drops under 5 V.

FAQ

Why are all 16 outputs on my 5069-OB16 flashing red?

Nearly always field power. On a Series B card, losing LA faults every point at once. Check the voltage between LA+ and LA- at the RTB before you suspect the module.

Does the 5069-OB16 need SA power?

It draws none. The outputs run on LA. It still needs to live on a DC SA bus, and it takes 75 mA of MOD power.

Why does an unused output flash red with nothing wired to it?

No Load diagnostic is enabled on that point. Uncheck it on the Points page or wire a load.

What does flashing green on the MOD light mean?

No connection to the controller. The configuration is missing, incomplete or wrong, and the module properties in Studio 5000 will show what's blocking it.

Can a 5069-OB16K replace a 5069-OB16?

Electrically, yes. Same ratings, same RTB, same wiring, plus conformal coating. It's a different catalog number though, so change the module in the project or Compatible Module keying refuses the connection.

Before you order a replacement 5069-OB16

If the checks above point at the card itself, IQElectro carries the 5069-OB16 and the faster 5069-OB16F. Whichever one goes in, read the series off the label, B if you want field power loss detection, and match the firmware to your project before it goes in the rack.