[SOLVED] Thermal Printer - Platon Release issue

Hello there

I am trying to interface 628MCL103 to the controller. I have a hardware issue. I am currently using LB1838 to drive the bipolar stepper motor and according to me it seems to be working fine. I see a smooth rotation but then the problem arises when i load the platen and the platen doesnot rotate at all. I am very much sure that i have inserted the platen in correct direction and properly.

Can anyone let me know what might be the possible reason. Is it because current or because its the load that causes issue.

As for now i am just trying to run the motor with platen inserted.

Regards
Sachin

I used to design similar thermal printer and I have memories of some similar problems - see the whole working and tested project published there:


https://www.edaboard.com/threads/6297/


As I remember the solution was to increase the speed of the pulses - initially you apply lower frequency pulses and then you increase the frequency. If you apply high frequency pulses to the step motor it's possible to "skip the pulses".

Luben

I have attached the schematic that i am using for the motor and also the LB1838M truth table.

The sequence that i am sending is as follows.

ENA2 IN2 ENA1 IN1

0 0 1 1;
1 1 0 0;
0 0 1 0;
1 0 0 0;

With these sequence the motors seems to rotate fine, atleast to the naked eye.

But when i connect the platen, its the same issue. I also have a reference board similar to the one that you had done which has serial interface. There is a slight difference that i find in the my device and the sample board, ie the sound which seems to be little rough compared to sample board. I guess the sequence might be the issue. I am not too sure about this as it looks perfectly good rotation.

Kindly suggest


Regards
Sachin

luben111 said:

I used to design similar thermal printer and I have memories of some similar problems - see the whole working and tested project published there:


https://www.edaboard.com/threads/6297/


As I remember the solution was to increase the speed of the pulses - initially you apply lower frequency pulses and then you increase the frequency. If you apply high frequency pulses to the step motor it's possible to "skip the pulses".

Click to expand...

Hi,
The sequence looks fine, if something could be wrong it is the frequency of this pattern (how often you repeat it). When you apply the sequence you get movement on one step. If you apply it too quickly the motor has inertia and can't follow the sequence - the result is that there is no movement. My point was that if you apply the sequence too quickly you'll not see the motor moving.

For beginning try to apply the sequence 10x slower and see the result.

I have checked from 300Us to upto 100mS. but with slower speeds, the motor seems to heat up after few steps. I also checked with each sequence by having a breakpoint and rotation seems ok.

I even tried applying a 0000 after 4 steps but the motor still heats and quite bad after some time.

As far as i know i dont need to even think of other pins of thermal printer now as i am just concerned about stepper motor rotation. All other pins are left floating as of now.

Regards
Sachin

Heating is normal when you apply slowly the steps. The question is - does it move correctly?

If it moves correctly then you simply need to smootly increase the speeds of the steps until you reach your target speed, for example you start with 10ms and you finish with 300us. The idea is that once the rotor starts moving you can apply higher frequency on the motor coils, until the motor is stopped you need to apply lower frequency and everything is because of the rotor inertia.

If the motor doesn't move correctly even on 100ms steps then you have problem - or the steps are not OK or the motor is damaged.

I guess when you speak that you apply the steps on 100ms you mean that each sub step is applied on 25ms.

Sorry for multiple replies.

The thing that i meant was 100ms every step. The platen still doesnot rotate. Its more like the gear slips and the platen kind of lifts up and comes back to the original position. I hope i am able to explain it properly.

Anyways i am thinking of getting one more printer and trying it.

Lets see if it works.

You need to check the step motor sequence - is it the producer recommended one?

Luben

I was finally able to rectify. I tried changing the hardware pins and it started working with 1ms delay.

It was a small hardware issue and it took almost 4 days

Meanwhile i am using 4 step sequence. I am hoping that it wont be of a concern in printing. Lets see...

Thank you for you valuable assistance.

Dear tiwari,

Even we are facing the same problem. We are using FTP-628MCL103#70-RB thermal printer for our project. All 6 strobes, paper sensor, thermistor signal and 4 stepper motor signals are pulsing fine. Now we stuck up with stepper motor rotation, we are following the same sequence which is given in the FTP-628MCL103#70-RB datasheet. We opened the retainer of stepper motor and we can see out of 5 wheels 4 are rotating as expected(before the platen is connected) . But the one wheel which is connected to paper platen is not rotating at all. Please find the enclosed schematic,



Could you please suggest the best solution to fix this issue.

With best regards,
Sujay