On Mon, Mar 23, 2015 at 7:17 AM, Erik Christiansen <dva...@internode.on.net> wrote:
> On 23.03.15 05:49, Mark Wendt wrote: > > On Mon, Mar 23, 2015 at 5:41 AM, Erik Christiansen wrote: > > > Though I am "a logic kinda guy", not a ladder wielder, I interpret > > > the "off" to refer to the B0 coil, not one of its contacts, which > > > may be NC or NO. That makes a NC contact an inverted output which is > > > a 1 when the input is 0. > > > > > > Does that realign the planets? > > > > I'm a comp sci kinda guy, so I'm familiar with logic too. ;-) > > > > According to the description, B0 and B1 are switches, not relays. > > Ah, true. Them's input switches, and the thing operates like a standard > No-Volt Release. > Yep. B0 and B1 are two different switches. B0 is NC and B1 is is NO. Here's the sentence above the offending one: "To turn the coil off one must momentarily open the 'normally closed' B0 contact which supplies 'power' to the whole line." According to this sentence, activating B0 turns power "off" on the line. > > Q0 is the relay. And it also says in the description B0 is normally > > closed. So, with that in mind, is "normally closed" off, and "open" > > on? > > Now the meaning seems to me to be that the switch is "on" when it has > been actuated, i.e. not in its default state. That will open a NC, and > close a NO contact. Just like any relay further down in the ladder, NC > and NO contacts are inverted and non-inverted outputs from a single > input gate, and have opposite logic levels for the same condition of > "on" for the relay/switch. (Boolean operations are implemented by > parallel/serial contact combinations on these outputs, not on gate > inputs, so a bit of A..-backwards nomenclature is needed to make it > simple, I think.) > > I don't believe the description is remotely coherent if "off/on" were to > be interpreted as "0/1" logic levels. > > Try it as I describe, and the diagram and text should align without any > clashing of mental gears. > The logic still doesn't match up with the simple switch diagram. B1 has to be activated for current to flow to the coil, to close the contact on Q0. B0 has to be in it's normal state. If you "activate" B0, you cut off the current and the contacts on Q0 open. So we have to determine what state the author meant for B0 being "off" or "on." Low or high, 0 or 1, NC or NO. ;-) ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
