Synchronizing E Series Devices

This section covers the signals commonly used for synchronizing E Series devices.

Analog Input Tasks

If you are synchronizing analog input tasks, you can do so by sharing the following signals:

• Master Timebase and a Start Trigger—All synchronized devices are programmed to use the same signal (usually the 20MHzTimebase from one of the devices) as their Master Timebase. More generally, one device can be queried for its Master Timebase source and that terminal can be set as the source of the Master Timebase for the other synchronized devices. All synchronized devices are programmed to use the same ai/StartTrigger terminal as the source of their Start Trigger. You can always share a Start Trigger even if you have not explicitly configured one. There are two advantages of using this method. The devices need not sample at the same rate, nor acquire the same amount of data. This method also works for synchronizing analog output signals and some counter applications. The disadvantages of using this method are two signals need to be routed using two RTSI or PXI trigger lines. An attribute/property must be set to designate the 20MhzTimebase of another device as the Master Timebase of a synchronized device.
• AI Sample Clocks—All synchronized devices are programmed to use the ai/SampleClock terminal from one of the devices as their Sample Clock. The advantage of using this method is only a single signal is routed using but one RTSI line or PXI Trigger line. The disadvantages are that all devices must sample at the same rate and can acquire no more data than the device that is sourcing the AI Sample Clock.

Analog Output Tasks

If you are synchronizing analog output tasks, you can do so by sharing the following signals:

• Master Timebase and a Start Trigger—All synchronized devices are programmed to use the same signal (usually the 20MHzTimebase from one of the devices) as their Master Timebase. More generally, one device can be queried for its Master Timebase source and that terminal can be set as the source of the Master Timebase for the other synchronized devices. All synchronized devices are programmed to use the same ao/StartTrigger terminal as the source of their Start Trigger. You can always share a Start Trigger even if you have not explicitly configured one. The advantages of using this method are that the devices need not generate samples at the same rate, nor generate the same amount of data. This method also works for synchronizing analog input signals and some counter applications. The disadvantage of using this method is two signals need to be routed using two RTSI or PXI Trigger lines. An attribute/property must be set to designate the 20MhzTimebase of another device as the Master Timebase of a synchronized device.
• AO Sample Clocks—All synchronized devices are programmed to use the ao/SampleClock terminal from one of the devices as their Sample Clock. The advantages of using this method are only a single signal is routed using one RTSI line or PXI Trigger line. The disadvantages are that all devices must generate samples at the same rate and can generate no more data than the device that is sourcing the AO Sample Clock.

Counter Tasks

You cannot synchronize counter input applications performing period, frequency, pulse width or semi-period measurements in the same sense as analog input or output applications. These types of counter input applications cannot be programmed to make their measurements at the same time because the signals being measured themselves determine when the measurements are made, and there is no reason to set up multiple devices to measure the same signal. You also cannot use Start Triggers for counter input applications.

You can, however, ensure that all counters are using the same timebase for their input measurements by sharing the CI Counter Timebase signal. Program all devices to use the same signal (usually the 20MHzTimebase from one of the devices) as their CI Counter Timebase. More generally, one device can be queried for its CI Counter Timebase source and that terminal can be set as the source of the CI Counter Timebase for the other devices.

If you are synchronizing buffered counter input applications performing edge counting, you can do so by sharing the Sample Clock. The Sample Clock must be externally supplied to one of your devices. The other synchronized devices are programmed to use this device's CtrnGate signal as their Sample Clock, where n is the number of the counter.

If you are synchronizing pulse generation counter output applications, you can do so by sharing the CO Counter Timebase and Start Trigger signal. Program all devices to use the same signal (usually the 20MHzTimebase from one of the devices) as their CO Counter Timebase. More generally, one device can be queried for its CO Counter Timebase source and that terminal can be set as the source of the CO Counter Timebase for the other devices. Program all devices to use the same signal as their Digital Edge Start Trigger. This is typically the CtrnGate signal from one of the devices, where n is the number of the counter.

Other E Series Synchronization Notes

PXI E Series devices use PXI_Trig 6 to receive PXI Star trigger signals. Thus, these PXI E Series devices cannot use PXI_Trig 6 to communicate with one another.

PCI E Series devices import 20 MHz Timebase clock only from RTSI 7. PXI E Series devices import 20 MHz Timebase clock only from PXI_Trig 7.