Ramps 1.4 No Temp feedback and movement

Hi

I am building a custom machine using ramps 1.4 board that i got from reprapworld with the SDcard.
I am using one of their Thermistor 100K B57560G1104F and nema motors

I have tested the board and axis with the test code and every thing flashes and all the motors move.

i have installed pronterface and it connects sort of reads the card returns lots of numbers and it turns on the extruder heater but the temp does not change also i cannot get any of the axis to jog.

What am i missing?

Hi Barry

Is the 'test code' an arduino sketch that just flashes the lights and moves the motors? If so, you have to re-flash the RAMPS board with a real firmware (Sprinter or Marlin, for example) before pronterface can talk to it properly.

I recommend starting with Sprinter, because I found the defaults for Marlin didn't work at all for my Prusa. Now that I've got the configuration sorted, Marlin works really well.

If you have already used the Arduino IDE to flash your firmware to the RAMPS, maybe try again, since you may have overwritten the firmware with the 'test code'.

And make sure you've got the same transmission speed selected in Pronterface (in the field next to the com port selector) as you have in the configuration.h file in your firmware. I use
#define BAUDRATE 250000
with great success, but some people find that unreliable on their hardware.

good luck,

Andrew Roberts
brazenartifice@gmail.com
brazenartifice.wordpress.com

I have re flashed the card (mega 2560) and i have set the card to 115 in the sprinter software with the SD card support. It compiles and download successfully.

I can get the extruder heat to turn on but get no feed back from the thermocouple and cannot get any movement from any of the steppers.

What is the minimum i can connect up to test this axis?

At the moment i have been trying with the x axis connected and jumpers on the limit switches. Do i need the Y Z Extruder connected?

Does the power led come on when connected or when something is active, as it only comes on when the heater is active at the moment.

I have tried to send G1X100. and G0X100 but nothing happens.

Have you chosen the right electronics in your sprinter configuration.h file? For RAMPS 1.4 you need to say
#define MOTHERBOARD 33

That should get you some readings from your thermistor, when you click 'monitor printer' in pronterface. I always recommend not even applying power to the steppers and heaters until you've got meaningful temperature readings. It is quite possible to destroy your hot-end through over-heating it, if your RAMPS board doesn't know what temperature it is.

In fact, until you get a temp reading of (if I recall correctly) above 5 degrees Celsius, the firmware should refuse to heat the nozzle at all. This is a failsafe to try to stop people melting their hot-end if their thermistor fails, or if their wiring comes loose (which happened to me a couple of times).

The readings from your thermistor will only be correct if you select the right thermistor in configuration.h For my 100k thermistor, as supplied by MakerGear, I use
#define THERMISTORHEATER 1

I seam to be reading 30 deg and 70 when nothing is connected

Do you mean 30 degrees for the nozzle and 70 degrees for the heated bed?

If you have the same type of thermistor installed for both the heated bed and the extruder nozzle, they should both return the same ambient temperature (plus or minus a degree or two) if you don't have the external power supply switched on.

Oh - have you hard-wired your heated bed directly to the 12V power supply? I hope not, because then the RAMPS can't ever control the bed temperature. If you have, that might mean that something (the bed, or the nozzle if you've got the thermistor connectors round the wrong way) really _was_ at 70 degrees. 70 degrees is a little too high as a bed temperature for PLA (60 is about the most you'd want), and too low for ABS (people seem to use 100 - which is the boiling point of water, just in case you're a non-metric person!)

If you have a heated bed, you need something like

#define THERMISTORHEATER 1
#define THERMISTORBED 1

if you don't have a heated bed, you'd use
#define THERMISTORHEATER 1
#define THERMISTORBED 0
instead, to turn off the bed heater

The numerals in those statements select which thermistor compensation table the firmware will use. If you use the wrong one for your thermistor, you'll get weird results. I once got something like 174 degrees as my ambient room temperature!

So if you are certain that your thermistors are connected correctly (to T0 for the nozzle, and T1 for the bed), and you are getting weird but non-zero room temperature readings from pronterface, you probably need to choose a different thermistor compensation table. I can't help with that, sorry.

I have a post on my blog with some slightly blurry photos of the connections to my RAMPS 1.4 board on my MakerGear Mendel Prusa. Maybe that might help.
[brazenartifice.wordpress.com]

Edit: Sorry, should have said that those photos were from before I installed my heated bed, which is why there is no connection to T1.

Edited 1 time(s). Last edit at 04/10/2012 07:11AM by BrazenArtifice.

I am getting 30 and 70 if a thermocouple is attached or disconnected. At the moment i have not got a heated bed connected.

If you get the same temp reading regardless of whether the thermistor is plugged in or not, then either

1: You've got the wrong motherboard type selected (must be 33 for RAMPS 1.4), which means the pin assignments are wrong. That'll mess up lots of other things too.

2. You've got the thermistor connected to the wrong pins on the RAMPS. Must be T0, not T1 or T2

3: your thermistor leads are not properly connecting to the RAMPS board. I hate molex connectors. Unplug the molex connector from the RAMPS board. Measure the resistance between the two sockets of the molex connector wired to the thermistor. You should get somewhere between zero and 100k ohms. Not zero, and not >=100k.

Zero ohms means your leads are shorted or the thermistor is dead. Infinite resistance means your leads are disconnected. For me, room temperature corresponded to somewhere around 80k ohms, if I recall correctly.

(4. Hopefully not. There may be a fault in the RAMPS board. This is especially likely if you soldered it yourself. Sorry to be so blunt, but not many people can solder as well as a machine. Certainly not me, which is why I bought a pre-assembled RAMPS board.)

I really can't think of any other reasons why it makes no difference to disconnect the thermistor. All my thermistor problems have been thanks to the evil molex connectors _looking_ like they were connected, but not _being_ connected. Especially the ones at the thermistor ends, because the thermistor leads are not designed for crimping, and I didn't have an appropriate crimping tool anyway.

I keep hoping someone else will chime in with an explanation I've never heard of before...

The issue seamed to be a 3 instead of a 33.

Thanks for all the help.

temp and x axis moving now

Great stuff. Thanks for taking the time to confirm the solution.

There is quite a difference between a thermocoupler and a Termistor, but by the looks of it you say thermocoupler but meant to say Termistor.

NO, I think he menat to write Thermistor!

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
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