Daniel, Marc, Fil, Richard, Erik, Dave:
Attached drawing shows the SUS ETMX DAC changes made yesterday.
Summary:
The new LIGO 28-bit DAC has replaced the h1susetmx model's 20-bit DAC signals. These comprise five L3 ESD signals, four L2 signals and four L1 signals.
The h1susetmx 18-bit DAC channels were not changed (the M0 and R0 signals).
The h1susetmxpi model's two 20-bit DAC signals were not changed, no h1susetmxpi model change was needed.
The routing of the h1susetmx model's L3, L2 and L1 signals to the 28-bit DAC was done using an existing matrix. Gains were applied using existing filter-modules. No h1susetmx model change was needed, this was a hardware change.
Details:
Please reference attached drawing and h1susetmx model snipet.
The h1susex front end comprises two ADCs, three 18-bit DACs, two 20-bit DACs and the new LIGO DAC. Setting the ADCs aside;
The third 18-bit DAC is only used by the h1sustmsx model, and so can be discounted.
The first two 18-bit DAC cards are used by h1susetmx (driving M0 and R0). These were not touched and are not applicable.
The first 20-bit DAC card is used by h1susetmx to drive L1 and L2 (four channels each).
The second 20-bit DAC card is shared between the h1susetmx and h1susetmxpi models. h1susetmx owns the first six channels, and drives five of them (L3-ESD DC+4QUAD). h1susetmxpi owns the last two channels (ESD left and right).
There are two types of Anti-Imaging (AI) chassis used here: the standard 18-bit/20-bit DAC AI (two inputs, each input is driven by a separate DAC), and the Parametric Instability (PI AI) chassis. The PI-AI has one input (block of eight channels) which internally are split into two blocks of six and two channels. The block of six channels is filtered normally and exits as chan 1-6 on front panel ('OUT 1-6'), the block of two channels is PI filtered and exits on its own front connector ('Band Pass Ch 7 & 8'). See attached photo.
Before:
The first 20-bit DAC is connected to one half of a standard AI chassis. Its output drives the L1, L2 signals.
The second 20-bit DAC is connected to a PI-AI chassis. The first 6 channels are driven by h1susetmx, the last two by h1susetmxpi.
The LIGO DAC is not connected to any AI chassis.
Now:
A second PI-AI chassis was installed in the rack, it is used to drive h1susetmxpi's DAC channels.
The first 20-bit DAC was disconnected from its AI (see note below).
The second 20-bit DAC was disconnected from the original PI-AI and connected to the new PI-AI. The PI driver cable was moved from the original to new AI. This means that other than the AI chassis change, the h1susetmxpi model and its drives were unchanged.
The first 8 channels of the LIGO DAC are connected to the original PI-AI (with its L3/ESD field cabling intact). Therefore the ESD analog filters were not changed in the transition from 20-bit to 28-bit DAC.
The second 8 channels of the LIGO DAC are connected to the standard AI (was connected to first 20-bit DAC). This permits drive of L1 & L2.
The attached MEDM snapshot shows the matrix/gain settings. The first 5 channels are driving the ESD, the second block of 8 the L1/L1.
Complications:
Initially the first 20-bit DAC (h1susetmx L1 & L2) was going to be left disconnected from any AI. However the lack of an AI watchdog signal put this DAC into error. Marc connected this DAC to a second input of a PI-AI chassis. This input does not internally connect to any filter block, but the interface card does supply the missing AI watchdog signal.
The IOP model's software watchdog (SWWD) needs to have the new LIGO DAC added to its DACKILL list, now that the new DAC is part of production.
