Hit time invalid error message while runing in simulink

Hello,

Simulation while runing in simulink was stopped and the following message was occurred.

"The next hit time(-429.4967296) for variable sample time(tid=4) is invalid because it is either less than or not sufficiently greater than the current time (429.49672949999996)."

Simulation constraints are like this :

• Accelerator mode
• solver options : variable step, ODE23, max step 1e-7, relative tolerance 1e-3, min step size, absolute tolerance, initial step size : auto

I am looking forward to your good opinion. Thank you.

[Walter Roberson]

As an experiment, try increasing the max step size to 1e-6

[Kyoung Ho Chong]

Thank you. But max step size is fixed to 1e-7 because of random data period. Any other solution do you think? for example, change of absolute tolerance to 1e-4~1e-6, one more, what is the relation between relative tolerance and absolute tolerance?

[Walter Roberson]

I am still wondering whether that message was talking about negative time? The number in () starts with "-" it appears.

[Walter Roberson]

Consider a tolerance of 1/1000, 0.001. Consider a value of 3000.

Absolute tolerance would be 3000 +/- 0.001 which would be 2999.999 to 3000.001 .

Relative tolerance would be 3000 +/- (0.001 * 3000) which would be 2997 to 3003.

[Kyoung Ho Chong]

Thank you. I think negative time("-") doesn't means any special sign in which the error message box wrote. Anyway, simulation is stopped at 429.xx sec. Your 1'st answer "increase the max step size up to 1e-6" is right because I was experienced. But system is operated a few MHz and random data is at least more than 10MHz, so unfortunately I can't. For a simular system, system clock is 5 times lower and simulation is stopped about 1500 sec. I want to solve this problem by adjusting other simulation parameters. I am looking forward to your good idea..Thank you.

[Walter Roberson]

Re-reading I think the problem is the min step size, that you should set it specifically and make it 1E-8 or smaller.

[Kyoung Ho Chong]

I tried to adjust the min step size from 1e-8 to 1e-12. But the result is not changed, still simulation is stopped at 429.xx sec. One more I've tried by changing Max step size into "auto" from previous 1e-8, but unchanged. Sorry for not giving a good result~. If you have any idea, anytime tell me. Thanks!!