J 325 Scrambled PIC?

[Forcedinduction]

Hi, all. Member here some years ago, been busy, forgot logon name.

I have a J 325 with the Delta 20 control that has been mostly trouble free until it recently developed a strange problem. It shows a Z axis overtravel message constantly, even though it is not in overtravel. I can trigger the OT prox switch and the machine will e-stop and display an e-stop message. That has always been the result of OT on the Z axis. Machine e-stops with no reference to the Z.

The current condition is not inhibiting program operation. But, the screen constantly cycles from whatever should be displayed at the moment to the "Z axis overtravel" message. I verified that 24 volts was present at the Z home terminal on the DC I/O input jack and even traced the signal through a few ICs on the board.

In a brief discussion with a tech, he noted that input was inconsequential, which makes sense since the Z OT prox switch directly controls a relay that puts the machine into e-stop. That, and the fact a true Z OT does not result in a Z OT message being displayed. He further suggested the problem was probably a corrupted PIC table but couldn't provide additional information. Lucky for me, I never took the time to record the few pages of PIC tables for such an occasion as this. Does anyone know what location in those tables would contain the bit that would turn off the error message?

Thanks.

[jagardner4]

Check the PIC to CNC table. Access the table by pressing the 'Fault/Status' key, then press the 'PIC Tables' soft key, then 'Page FWD' twice. Locate Word 34, which is the first 16 fault messages. When the 'Z Overtravel' message is active, verify that bit 'D' is on (has a '1' in it). The logic for this message is tied to DC input 23, which can be monitored on the first page of the PIC table at Word 1, Bit 7. Unfortunately, I don't have the original listing, so I'm not sure how the logic should work.

BTW, the PIC program itself is probably okay. Usually when the PIC EEPROM goes bad, whole sections of logic disappear - and the machine quits working entirely. I would suspect either the DC input circuit or the actual device feeding the input.

[underthetire]

Possibly a PIC table, but I would check soft limits first. The alarm you are getting is soft limit overtravel, probably nothing to do with switches. I would go in to the setup page and make the Z limits + and - 999, then zero return. Re-set them for +.1 or so and - 5.9. (or there abouts). If you get them wrong you will end up in a hard limit and will have to remove the access cap for the Z and use a screwdriver to turn the axis off the limit.

[Forcedinduction]

Guys, thanks for the suggestions. Here is what I have found so far.

Resetting the travel limits had no effect. I eventually ended up with them back at -6.000 and +.000 where they were. I hoped that might work. When I jogged to some reduced soft limits, I had a Z limit error message in addition to the OT message that is plaguing me.

The D bit in Word 34 is set (1) as is bit 7 in Word 01.

Interesting, the wiring diagram I have, not original to this machine, shows the hardwired input for Z Home to be at terminal J1-19 with the PIC entry for that input being W1-0.

Input J1-23 (W1-4) is shown to be tied high for the 6000 RPM spindle, which this machine has.

To verify, I checked and found 24 volts present at inputs J1-(17-19) and 23. My drawing shows J1-17(W0-E)=X Home, J1-18(W0-F)=Y Home, J1-19(W1-0)=Z Home.

A tech at Parts and Smarts told me a couple years ago that the wiring on the 325 changed frequently during its production. I don't know.

If input 23 controls the Z OT message, I'll need to go back and trace it through the board. Any other suggestions?

Thanks.

[underthetire]

I'm not sure what you are seeing. J325 do not have home switches on the aixis. I would not expect to see 24 there?

You sure this isn't a - switch, like a pull down style? No prints here for Tree's any more so I can;t look it up

[Forcedinduction]

I'm not sure what you are seeing. J325 do not have home switches on the aixis. I would not expect to see 24 there?

You sure this isn't a - switch, like a pull down style? No prints here for Tree's any more so I can;t look it up

You are correct, no home switches. The drawing I have indicates those inputs are hardwired to 24 volts. My checks indicate that they are.

[jagardner4]

The "home" switches would have been used to reference the axes. They really have nothing to do with overtravels. It is correct that the J325 did not have reference or home switches - the inputs were tied high to look like the axis was sitting on the switch, the user was asked to line up arrows on each axis, then reference at that point.

If the PIC table indicates an input is high (1), there is no reason to check the hardware circuit. The PIC table will reflect exactly what's going on at the card.

Bit 7 of Word 34 indicates the 'Drawbar is unclamped' message is on. If you're not seeing it on the screen, then the information (text) is not on the parameter EEPROM. I've seen where portions of the coding for the PIC and/or parameters gets "lost" off the EEPROMs after so many years. This may be the case here.

The only place I know that has a copy of the J325 PIC program is DynaPath (where I'm at). Unfortunately, I have to charge customers to create a new EEPROM (if we have the right one). Parts and Smarts may be able to help as well.

[Forcedinduction]

The "home" switches would have been used to reference the axes. They really have nothing to do with overtravels. It is correct that the J325 did not have reference or home switches - the inputs were tied high to look like the axis was sitting on the switch, the user was asked to line up arrows on each axis, then reference at that point.

If the PIC table indicates an input is high (1), there is no reason to check the hardware circuit. The PIC table will reflect exactly what's going on at the card.

Bit 7 of Word 34 indicates the 'Drawbar is unclamped' message is on. If you're not seeing it on the screen, then the information (text) is not on the parameter EEPROM. I've seen where portions of the coding for the PIC and/or parameters gets "lost" off the EEPROMs after so many years. This may be the case here.

The only place I know that has a copy of the J325 PIC program is DynaPath (where I'm at). Unfortunately, I have to charge customers to create a new EEPROM (if we have the right one). Parts and Smarts may be able to help as well.

I sort of mixed information together there in one sentence. It is bit 7 of word 1 that is set.

I had guessed that maybe the absence of a high on an "axis home" input would cause an axis OT message to be set. It is odd that the X and Y axes have an OT input but the Z only uses the prox switch to effect an e-stop. Difficult to figure where the Z OT message would originate.

Was PIC table information usually supplied with machines? This one came to me with only the Tree installation and maintenance manual and the Dynapath Programming (?) manual.

Thanks.

[jagardner4]

Tree wrote the ladder logic (PIC) for all their machine. I don't believe they supplied ladder listings with the original documentation. As to the I/O tables, the DC inputs and DC outputs can be obtained from the Tree electrical prints (the machine OEM assigned where the I/O was in the ladder) and the CNC to PIC and PIC to CNC tables were the same across all Delta 10/20 mill controls.

I believe the error message you are getting is being turned on erroneously because the PIC programming in EEPROM has started to degrade. When this begins to happen, what you see in trying to troubleshoot will not make sense. The DC input at Word 1, bit 7 being on (1) is correct and should inhibit the message. Because the message is still being displayed, I can only conclude the PIC program has changed.

[Forcedinduction]

I appreciate the help. One more question. Is it possible to look in the parameters to see if there is an incorrect value that could cause this problem -and enter the correct information? The documentation I have is quite limited.
Thanks.

[jagardner4]

No. Parameters are stored on an EEPROM on the processor board. The PIC is stored on an EEPROM on the PIC board. There is no parameter in this case that will affect how the PIC is working.

[zpsbob]

There was only a handful of J325s that used the switches for reference/home.

Most machines those switches are only for hard OT. Soft limits on that machine should be +.001" / -6.001". If it is set to +0.000", then it will get OT alarm when referencing. The axes reference to the next marker pulse on the motor only (unless you have one of the very very few oddball machines)