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step-motor controller/driver connection
Dear folks,
As you may know, we have been designing transition boards to connect
Oregon Microsystems VME8, VME44, and VME58 controllers to motors--in
particular, to the 20-pin ribbon-connectors found on the Advanced
Control Systems Step Pack (MDU8). The new Step Pack currently under
development (SPR9 rack, SPD6U drivers, SPT8 transformer, and as yet
unidentified interface module) can have the same or different interfaces
to controller electronics, since the interface is a replaceable module
that goes in the ninth slot of the rack-mount chassis.
I know Leo Bric at ACS plans to develop a serial-input indexer as one
possible interface, and I've suggested two other interfaces. The first
is obvious: simply a reproduction of the current Step Pack interface;
the second is intended for situations in which the driver electronics
are located remotely from the controller (e.g., in the experimental
station). In this case, I'm not comfortable with single-ended
transmission of any edge-sensitive signals. I also want to support
unbundled drivers without producing too many different transition
modules.
So I plan to suppport an interface module for the new Step Pack with
eight DB-15 connectors (one per motor, so the same transition board can
also be used for unbundled motor drivers) whose pinout is described
below. I'd like comments as quickly as they occur to you, since we're
all under some time pressure.
==========================================================
VME58 <--> (New Step Pack OR isolated motor drivers)
----------------------------------------------------------
Pin Dir Function Pin Dir Function
----------------------------------------------------------
1 Out step + 9 Out step -
2 Out direction + 10 Out direction -
3 In high limit switch 11 In low limit switch
4 In encoder A + 12 In encoder A -
5 In encoder B + 13 In encoder B -
6 In index + 14 In index -
7 In home 15 Out auxiliary
8 ground/shield
Justification:
--------------
Kurt Goetze has found a board-mountable stacked pair of DB-15
connectors, which greatly simplifies the fabrication of transition
boards, so we really want to go with this connector unless there's
some killer issue we've not addressed.
There aren't enough pins to go differential on any level-sensitive
signals (limits, home, aux), so the transition board will have
capacitors to improve noise immunity. (Limit- and home-switch
inputs would have to be debounced in any case, so there would be
little point in differential transmission.)
-------------------------------
Well, what do you think? Does anyone already have a similar
standard in use? Does anyone want us to produce transition boards
for their CAT while we're making a bunch for SRI-CAT? Is anyone
else asking ACS for a similar interface module? Is there interest
in a similar transition board for VME8 and/or VME44?
Tim