The 182 has two words of digital output. Every property of a data base device can access one word, or some fraction out of that word. The way to set up a 'fractional word' device (or property) is to bake a mask into the SSDN, which defines which bits belong to this property. Thus it is theoretically possible to define the Setting property for some device as addressing the high byte of one 182 word, and the Basic Control as addressing the low byte. For the Setting you define a mask of FF00, for the status you define a mask of 00FF. The SSDN is thus: Word 0: mask mask defining which bits belong to this device/property. Word 1: 0020 OID Word 2: ccnn crate and slot Word 3: 20fa a =subaddress (0 or 1) f = 0 (modes 1&2), f = 1 (modes 3&4) This SSDN can be defined for both Setting and Basic Control properties. Reading-the-setting will return the current state of the 182's bits for this device. When you actually transmit a new word to the 182 we support two modes of operation: simple settings and pulsed settings. You can run both the setting and basic control properties either D.C or pulsed. Furthermore this choice is made by the data you send. It is not baked into the SSDN. For simple (static) operation send down a single word with the new setting. The mask in the ssdn will be written to the card, followed by the new setting. Only those bits in the setting which are allowed by the mask will get changed. If you send two words, and the second word is zero, then the same static operation applies. To invoke pulsed operation send two words: the pulsed value and the 'pulse mask'. The pulse mask and the ssdn mask are combined (anded) to form a (possibly smaller) mask. The pulsed value is written out under this new mask. One second later we complement and write. The net effect is a 1-second pulse on the selected bits. An example may be in order. Suppose we want to define Basic Control to be the 2 high order bits on the high order 182 word: bit 2**15=on/off (static) bit 2**14=reset (pulsed) We then set up our Basic Control in the data base: ssdn = 20FF nncc crate and slot 0001 subaddress 1 (high order word) C000 upper 2 bits belong to this device max length is 2 words (so we can pulse) pdb = length is 2 words ON mask = 8000 (low word - turn bit 2**15 on) 0000 (high word - no pulsing) OFF mask = 0000 (low word - turn bit 2**15 off) 0000 (high word - no pulsing) RESET mask = 4000 (low word - turn bit 2**14 on) 4000 (high word - pulse bit 2**14 back off after 1 second) Now suppose we have a 16 bit static Setting for the other 182 chan: ssdn = 20FF nncc crate and slot 0000 subaddress 0 (low order word) FFFF whole word belongs to this device max length is 1 word (static operation) pdb = anything that scales to a word full of bits. It is also possible to assign a 182 to a Reading or a Basic Status property, in which case you will read back the current state of the bits belonging to the device. This is the same as reading-the-setting.