Spectracom GSG-5 series, User Manual With Scpi Manual

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6.6 Programming
6.6.1 Usage Recommendations
6.6.1.1 Communication Interface
It is strongly recommended to use USB in conjunction with RSG. USB is more reliable due to
being a dedicated interface as opposed to Ethernet which can be more susceptible to network
traffic. Ethernet should hence be avoided if attempting advanced steering using high message
rates or requiring synchronization at the GSG 10Hz epoch rate.
GPIB can be used as an alternative but as there are synchronisation issues with GPIB, USB
remains as the number one choice.
6.6.1.2 Synchronization
It is possible to synchronize SCPI commanding with GSG’s internal processing loop, with a res
olution of 100 ms. This can be achieved by using the
*WAI
and/or
*OPC?
commands.
For example, checking that the ECEF position command is applied on next 10 Hz epoch:
sour:scen:ecefposition IMMEDIATE,1000.0,2000.0,3000.0
*OPC?
sour:scen:ecefposition?
This synchronization can happen irrespective of whether an RSG command comes in.
For example, to see elapsed time “ticking” in 100 ms epochs
*OPC?
sour:scen:elapsedTime?
*OPC?
sour:scen:elapsedTime?
In addition, this synchronization mechanism can be used to consecutively to achieve any
desired synchronization rate (max resolution of 100 ms, ie. at 10 Hz). For this purpose only
*OPC?
should be used. To use
*WAI
for this purpose the user would need to insert a small
micro sleep, or perform suitable actions, between consecutive
*WAI
commands.
For example, to see elapsed time “ticking” every half a second the following commands can be
looped:
...
*OPC?
sour:scen:elapsedTime?
*OPC?
6.6 Programming
CHAPTER
6
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User Manual GSG-5/6 Series Rev. 26
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