10/10/91 (rev) Front End Support for the 5408 DACs The Bi Ra 5408 is an eight channel simple DAC controller. Each channel can be strapped as either unipolar or bipolar, and each can also be strapped for 10.0, 5.0, 2.5 volt full scale operation. The card is extremely simple: F(16)A(N) writes a DAC value, F(0)A(N) reads it back. The front end supports the Setting, Reading, and Basic Control properties only. Reading is the same as reading-the-setting. Basic control is the same as setting: the basic control word received by the front end is set into the DAC as an analog voltage. This option warrants no further description. The SSDNs for all three properties look like this: +----------------------------------------------+ | Dev type=119 (77 hex)| FF (hex) | +----------------------------------------------+ | 'N' slot | 'C' crate number | +----------------------------------------------+ | Strapping option | subaddress (0 - 7) | +----------------------------------------------+ | Ramp rate | +----------------------------------------------+ Code for strapping option: 0 = 10.0 volt bipolar 1 = 5.0 volt bipolar 2 = 2.5 volt bipolar 3 = 10.0 volt unipolar 4 = 5.0 volt unipolar 5 = 2.5 volt unipolar In Dabbel this looks like: SSDNHX SETTNG (77FF/nncc/ddaa/rr) cc - Camac crate nn - Camac slot aa - subaddress (0-7) dd - strapping option code rr - ramp rate (may be zero) In the database, the setting PDBs for these devices ALWAYS use primary transform number 2, which is signed 10.0V full scale. This is a fairly standard control system view of an A/D value. The front end is responsible for the auxilary shifting necessary to transform between this standard form and the form needed by the card. Setting data is two bytes long. Setting values which exceed the full scale limits set by the strapping on the card are clamped by the front end at full scale. If the "ramp rate" is zero, then DAC settings happen immediately upon request. If the "ramp rate" is non-zero, then the DAC is slowly ramped up or down from its current value to the requested value. The value of the ramp rate is in LSBs per 1/15 sec., so that a value of, for instance, three, will ramp at 45 LSBs per second. Extracts of Annotated Sample DABBEL Input -------- -- --------- ------ ------ ----- EMX (0532/0F0E/0301/0) | | | | | +-- DAC Channel 1 (right byte), strapped for +5 V unipolar | +-- Camac slot (left byte) and Camac crate (right byte) +-- Magic EMX numbers (=category 5 alarm from front end node 50) SSDNHX SETTNG (77FF/0F0E/0301/4) | | | | | | | + Ramp to new value at 4 LSBs/sec | | +-- DAC Channel (right byte), and strapping (left) | +-- Camac slot (left byte) and Camac crate (right byte) +-- Special SSDN Camac module identifier (77FF = 5408 DAC) PRO SETTNG (2, 2, 60, 0) | | | | | | | +-- Force the database to remember your last set value | | +-- 1 second default display update rate | +-- Maximum size of datum = 2 bytes +-- Default size of datum = 2 bytes PDB SETTNG ('DacV', 'kV', 2, 6, 2, 0, 0, 0, 1.0, 1.0) | | | | | | | | | | | | | +-- C2 | | | | | +-- C1 | | | | +-- Size of datum to convert = 2 bytes | | | +-- Common transform: f(x) = C1*x / C2 | | +-- Primary transform: 10.0 V signed full scale | +-- Physical (engineering) units (after both transforms) +-- Primary units=D/A V (after only primary transform has applied) SSDNHX READNG(77FF/0F0E/0301/0) ! Like setting, ramp rate ignored PRO READNG (2, 2, 60) ! Like setting, no setting value PDB READNG ('DacV', 'kV', 2, 6, 2, 0, 0, 0, 1.0, 1.0)