Temps reading high, using AD595 with Thermocouples

I decided to create a new thread since I solved the endstop problem. I'm still having problem with the temps reading high for the two extruders using thermocouples and the AD595 board. They were reading correct with the original version of Marlin 1.0.6. See full explanation of problem below.

I've had an AirWolf HD2 for over three years and last year I upgraded it to E3DV6 Volcano hotends with thermocouples. I made the required changes to the firmware for the AD595 thermocouple board and that has been working great. So now I want to add the BL Touch probe for automatic bed leveling but this required a firmware upgrade.

The original version was 1.0.6 which did not have the code for the BL Touch so I updated the Arduino to 1.8.5 and Marlin Ver 1.1.8. The Motherboard is a Rambo 1.3L so I uploaded the Arduino 1.6.4+ Board Manager Plugin from [raw.githubusercontent.com] and followed the instructions at [reprap.org].

I went thru the Configuration.h sketch and made the changes to fit my printer and checked the pin assignments in pins_RAMBO.h. Since I'm using thermocouples with the AD595 I entered #define TEMP_SENSOR_0 -1 and #define TEMP_SENSOR_1 -1, which was the same as the old program. I also changed the #Define Motherboard from 301 to Board_Rambo as called out in the Rambo Firmware instructions.

When I uploaded the new program all seemed OK with the exception that Temperature for Temp0 and Temp1 read about 470ºC, (Bed reads correct but that still has the thermistor).

I can only assume that there has been some other changes that is affecting the pin assignments. I tried to follow the code logic through the program, I define TEMP_SENSOR_0 as -1, but when I follow that the only coding I see for that is this:

#if MB(RUMBA) && (TEMP_SENSOR_0 == -1 || TEMP_SENSOR_1 == -1 || TEMP_SENSOR_2 == -1 || TEMP_SENSOR_BED == -1)
// Disable RUMBA JTAG in case the thermocouple extension is plugged on top of JTAG connector
MCUCR = _BV(JTD);
MCUCR = _BV(JTD);
#endif


I don't have a Rumba motherboard, so where is the code for a Rambo board?


Rick

Using the thermo-coupler with the AD595 amplifier board means you have a positive and a negative leads, reversing the leads would cause the the Ramps 1.4 to miss understand the input as shorted (zero ohms).



Pins 1, 4, 7 and 13 are ground.

If you trace the ground power wire to the output you see that this wire has to be wired to ground, the other is wired to thermister input to ramps 1.4 circuit board.

Aha! While that was not the problem it did get me checking the wiring to the board and I found it! Sometime during the wiring of the BLTouch I must have knocked the plug loose from the AD595 board to the Motherboard. I reconnected it and all is well. I was so stuck on a coding error I never checked the wiring. THANK YOU!

This brings back memories of the early 80's, working on a 8088 processor (4mHz) and staying up all night only to find the error, I had used a comma instead of a period.

Thanks again for taking time to reply.

My memories takes me back to the mid 70's hand coding assembly language on paper for the SWTPC 6800 college paper.
Then coding the Z-80 microprocessor for my Radio Shacks first computer TRS-80 - 4K memory and black /white monitor 0-127 pixels horizontal and 0-47 pixels vertical graphics.

Happy to post an ideal that helped you find your solution.

Edited 2 time(s). Last edit at 03/22/2018 08:47PM by Roberts_Clif.