100kHzTimebase source

[jrolston]

Hi all,

In M series devices (PCI-6259s, especially), is the source of the 100kHzTimebase the 10MHz reference clock?  So, if I were to use a RTSI line to provide a reference clock to the card (e.g., from another PCI-6259 card), the local 100kHzTimebase would be derived from the other card's reference clock?  Or is it always derived from the onboard clock?

Thanks,

John

[stilly32]

Hey John,

Check out the Digital Routing and Clock Generation (9-1) section of the M-Series user manual. The 100k timebase is just a divide down of your 20MHz clock, which can be pll'd to another cards reference clock. So your 100kHz clock will remain phase aligned with the other cards time base.

cheers,
Andrew S

[Brad_K]

Hi John,

In addition to what Andrew said, here's a word of warning: when you synchronize reference clocks on multiple M Series boards, the 100 kHz timebase signals will all be synchronized to the same reference clock but not to each other. This is because the clock divider used to generate the 100 kHz timebase from the 20 MHz timebase will not necessarily divide at the same time on each board.

Brad