J. Kissel

There're been reports that the primitive "just get it going" digital infrastructure to support the PZT drive system of the M2 stage of the HAM Piezo Double Suspensions (HPDS, PSAMS, P-SAMS) ZM2, ZM4, and ZM5 (see LHO aLOG 59992) are behaving in a way that's counter intuitive to users (see, e.g. LHO aLOG 60417). 

Repeated here and explained for convenience: because the HPDS PZT driver (chassis: D2000486; actual board: D060283-v4) has an internal -10V offset applied before it's gained up by x10 -- such that the *output* of the driver has a nominal range of 0 to 200 V (see page 4 of T2100056) -- then as the current infrastructure stands, sending a 0V request out to h1tcscs's DAC actually results in a 100 V PZT voltage. That also means that upon computer reboot -- if a digital offset is not stored in the TCSCS SDF safe.snap file, then upon a computer boot, the PZT get's "slammed" immediately to 100 V. No bueno.

As such, I propose infrastructure that follows the attached images. (Recall the "before" picture is shown in LHO aLOG 59992)
The infrastructure has the following changes, and design intent:
    (1) I changed the top-name of the block from "AWC" to "SUS," and added a callout to which stage the PZT actuator infrastructure lives. This way, the channel names will make more sense on the SUS MEDM screen (and to various automatons like the guardian), i.e. 
        H1:SUS-ZM2_M2_${function}
rather than
        H1:AWC-ZM2_${function}
    (2) Include a user-controlled master switch. Thus is such that the user (and a future automaton) can have the final say as to whether there's signal going out. 
    (3) Added a EPICs input variable to hold a permanent offset that reflects the electronics hardware.
    (4) Added an additional filter bank, PZTOUTF, after the sum of the SAMS bank and the OFFSET bank. This filter will be designed to be the calibration of the drive -- this way the SAMS and DRVR_OFFSET banks can be calibrated into the more natural PZT voltage units.

All of this infrastructure now lives inside a new library part, as well
    userapps/release/sus/common/models/HPDS_M2_MASTER.mdl
and this library part is copied and pasted to each ZM. So, if we don't like this layout, or want to add more eventually, we only need to change it in one place, rather than by-hand copy it from ZM to ZM, risking mistakes.

I've committed both the new library, and the change to the top level 
    userapps/release/tcs/h1/h1tcscs.mdl
to the svn, but will wait for an opportune time to install, since folks are still actively commissioning the ZMs today.
I have also not yet started to change the HPDS MEDM screens yet to support this change, but that will also come after heavy use on the SUS has calmed down a bit.