[Jeff_Y]

A client has a Mazatrol T-2 that displays the following error on startup "20 NMI Emergency Stop". Also the power ON and power OFF LEDs next to each button are both ON when the power ON button is pressed.

To cut a long story short it appears as if the PLC program is not being executed. e.g. According to the PLC program the PON relay (PLC output Y024, memory address H044.4) should turn on as soon as the operators power on button is pressed. This does not happen. The relay can be turned on manually via the diagnostics page (setting bit 4 of H044). When this happens the error message clears however this does not solve the problem.
Has anyone experienced the above symptoms ? And what could the cause be ?

Jeff.

[Philabuster]

"20 NMI Emergency Stop" will come up if E-stop is pressed in. I'm guessing it's not--right? Are there any other alarms on the Diagnostics page?

Inside the back panel electrical door on my QT, there is several small, black circuit breakers (near the clear plastic relays) that look about the size of a regular home light switch. If there is a fault, these breakers can trip giving this alarm. They are real sensitive. I have tripped them by merely brushing up against them.

Alarms can also show up if he lost any parameters. Are there any asterisks (*) in the parameters?

[chippy1]

Check your 24 volt supply from the cnc power supply. You mat also have a lambda external 24 supply also that needs to be checked. Sound like you have a short some where.

[Jeff_Y]

I have checked all the NC supply rails - all spot on.
There is also a separate 24 V supply for the relays - this is also OK.

The NC rack powers up OK - IT light flashing, RD light ON for the FX715 card.

[quickturngreg]

You may have a spindle drive problem (FR-SE, or FR-SF).

A malfunctioning spindle drive can prevent the Mazak from powering all the way up.

[southern cnc]

My Slant 40 does that when the air compressor is not on.
Most Mazaks do not look at the air pressure switch, however.
Good luck.

[nlh]

Check out this thread,

Need Help! NMI 20 Emergency Stop Alarm - CNCzone.com-The Largest Machinist Community on the net!

This concerns an M2 powered mill but I would think it would be the same or at least similar for the T2.

Good Luck!

[Woody111]

If you can force the bit on and the error goes away sounds to me you need to look at the ladder and see what else is not being statisfied in that line.

[cncserveng]

You are all giving good advise, but I would look and see if all the start preconditions have been made. You should be able to follow the electrical drawing and see which 24v input is missing. Or, if you have a ladder logic hard copy, use the "I/F Check" page to check the input and outputs.

This error i think is the Mitsubishi "020 emergency" caused by an external problem. (Mazatrol is Mitsubishi Meldas hardware)

Start conditions may include spindle and axis drive ready signals, also air pressure etc;

[chippy1]

Out of curiousity, how many ROM chips do you have on the FX715 PCB? Is there 6 or 8?

Chippy

[Jeff_Y]

The FX715 board has 6 EPROMs on it.

The ladder logic for the SB.M (H044.4) output which controls the PON relay is:

PCRUN PCRDY
H09F.7 H09F.3
---||---|----------------------------------------( )-----|
PCRUN |
H09F.7 |
---|/|---

.
.
. Several pages of ladder logic
.
.

PCRDY SB.M
H09F.3 H044.4
---||----------------------------------------------( )-----|

So you can see that when the top rung is executed it does not matter what condition the PCRUN relay is in PCRDY will always turn on.

The second rung shown will then simply turn on SB.M (NC REDY) and this output turns on the PON relay.

If you look at the electrical diagram one of the operations of the PON relay is to turn off the NC power off LED on the operating panel. This is NOT happening for this machine. Can someone check the state of the above relays for there machine (T-2).

I still believe the PLC program is not being executed. There must be some other hardware signal inhibiting the FX715 board from operating, however all the LEDs on it appear to be showing a normal state.

I have checked the 7 emergency stop conditions e.g. thermal trip, air pressure, hydraulic pressure etc. all OK.

[chippy1]

Did you happen to check the switches on the FX715 card. One of them will turn the PLC off. Also, if this is not the problem, please indicate what parameter OP7 is set too?

Regards,

Chippy,

[Jeff_Y]

There is a single dip switch on the card and I have tried it in both positions - no change to the symptom.

As for OP7 the manual I have does not list it - only up to OP6. Can you tell me the program addresses for OP7 (eg OP1 bit 0 is H11A.0 according to our manual)?

[chippy1]

Jeff,

OP7 is a parameter. You should be able to tell me the bit settings for 0~7 whether they are set to a 1 or 0.

Thanks

Chippy