sample time error for simulink model consisting of xilinx block sets

we have designed a model with xilinx block sets .i given sample period 10 ns . while running it is showing fallowing error.

The periodic sample time 1000000 is not allowed because the ratio of this sample time over base rate (1e-008) is greater than the maximum value of uint32.

Answer 1

[Kaustubha Govind]

The error appears to be pretty clear. Do you have a sample time of 1000000 anywhere in your model? You either need to reduce that sample rate, or increase the base rate of your model.

If you have not set such a sample-time in your model, it seems like other people have run into this issue with System Generator before. I would recommend contacting Xilinx Support for help.

[Lijo]

Hi,

My name is Lijo. I am facing a prolem similar to a posting from you in http://www.mathworks.com/matlabcentral/answers/40428.

In my case, I have 5e6 sample value. I used timing legend and it shows that my system has values of sample periods less than 1 (as I expected) to 1e6 sample values to 3e6 sample values to 5e6 sample values. Additionally none of the blocks or signals with values greater than 1 are highlighted even though the legend dedicates colours and annotations to them.

In the link above you suggested to reduce the sample time. 1. how? how do I atleast locate where it is? 2. as you suggested if I 'increase the base rate of your model' then my simulation slows down doesn't it? I am using Xilinx sysgen and trying to design hardware models using hwcosim.

Thanks. Hope you can help me out. Have a nice day.

Lijo

[Kaustubha Govind]

Lijo: Did you mean that you are running into the same error? If so, the reason not all the sample-time colors are highlighted could be that Simulink runs into the error during sample-time propagation and could not finish highlighting the colors. Most blocks have a 'Sample Time' parameter - find the blocks with the smallest sample-time and increase those.

[Lijo]

Hi, thanks for the reply. Well, the Simulink runs fine but then on the sample legend, it shows that I have sample times than run inti 4e6 and also 5e6 with (orange) color but it does not highlight which block takes so much time.

Additionally, how does Simulink calculate this sample time of say 3e6 or 4e6? I do not think I have specified anywhere such sample times. If the sample times can be manually changed. How?

I do not intend to change my base rate (0.000246) which could otherwise end up with faulty simulation results. So, reducing the sample period is the best option I think in my model. So 1. How is this sample time calculated by Simulink? 2. Can I change it manually?

Thanks a lot Kaustubha !

Lijo

[Kaustubha Govind]

Have you tried the Sample Time Display to 'All' to see where the large sample-times are originating. Typically it is one of the blocks in the path with the sample-time that specifies it.

[Lijo]

Yes I did. I have a multi rate system with blocks running at integer multiples of each other. I use some down samplers to synchronise them.

Interestingly, all the blocks which run with sample times less than 1 are colored and shown on the sample legend while those sample times more than 1 (in my case are 1e6,2e6,3e6 etc) are colored and given annotation on the Sample Legend but not identified on the blocks.

All my blocks are supposed to be running at sample periods below 1 and my input arrives at a sample period of 1. All the multi rated blocks are colored and shown correctly on the Sample Legend. There are also a few hybrid blocks !

Hybrid blocks have their own color representation but I don't think they can be the villains in my design. I am really clueless which block takes 5e6 sample time while I have specified only sample times less than 1 or inherited the sample times from blocks which have sample times less than 1.

Am I clear to you? Have you come across such scenarios? Thanks a lot again. Hope you can help me out !