"Two Signal" interfacing on BOB

[charisbill]

I see in the Announcements at the top of the page that MSM supports "Two Signal" interfacing using two input pins on the Break out Board. Can you point me to some instructions on setting up the two inputs and configuring MSM. I apologize if I have missed this discussion on the forum.

[DaveCVI]

Hi,
How to set this up is documented in section 6.1.3.2 of recent versions of the MSM mill user manual.
If you need the manual is can be found here:
http://www.calypsoventures.com/download ... lease.html

There has not been a lot of discussion of this feature on the forum - as far as I know it is just working for those that have decided to use it.

Dave

[charisbill]

I'm pretty new at both Mach 3 and Mach Std Mill, so I apologize for what may be some pretty basic questions. I'm assuming the 3D probe input has it's input defined under Config , Input Signals, Probe (port 1 pin11, in my case). Now, since the Touch Plate is a separate input, which input signal do I use? Index? Input #1, OEM Trig #1???

[DaveCVI]

Hi,
No problem re questions. That's what the forum is for.

The two signal interface uses a special call into mach that allows MSM to either look at the probe or the touch plate.
I'll skip the technical background and say that the config is:
1) Connect the probe to an input pin, assign that input pin to the "probe/Digitize" signal in ports & pins. (some places in mach call it Probe, other places it is called digitize - both names mean the same logical signal).

2) connect the touch plate to another input pin; in ports & pins assign that pin to the "timing" input signal.
That gets you the ability to use both probe and TP without needing additional electronics.

Be sure to set the polarity of the two pins to match the devices you are using. Most probes are active high, and touch plates are active low.

Dave

[charisbill]

Thanks Dave. That should get me going this next week. I don't seem to be able to find this info anywhere in the manual. Am I missing it? I have the latest manual from the link you provided and there is no section 6.2.3.2. Section 6.3.2 has good info about the probe interface issues, but I don't see anything about using the "timing" input signal.

Bill

[DaveCVI]

Whoops, sorry - my earlier post said 6.2.3.2 and it should have been 6.1.3.2....
In the newest manual it's pages 133-136.

FYI - Below is the text contents of the section.
Dave
______

6.1.3.2 Two signal Interface
For users that are not comfortable building the interface electronics described in section 6.1.3.1,
active high and active low devices can be combined at the Mach logical signal level instead of the
hardware input pin level. This is referred to as the “two signal interface”.

Taking this approach requires the use of two input pins at the control. This approach also
sacrifices the ability for the GUI to show the state of all probe input devices at all times. In
exchange, the hardware complexity is reduced to attaching a send wire to a second terminal on a
break out board.

With the one signal interface, MSM uses the Mach Probe input signal and assumes that all probe
event input devices drive the single input pin (and hence the single “probe” input signal).
In contrast, with the two signal interface, the probe device is interfaced to a pin that is logically
connected to the mach probe signal, and the touch plates are interfaced to a 2nd pin and an
alternate mach signal. This removes the need for the external interface electronics at the cost of
using one additional physical input pin & one more input signal into Mach.

When configuring the “two signal” interface, the probe and touch plates are wired to different pins
of the break out board.
- The Probe tool must be connected to the mach Probe input pin and the Probe signal
must be enabled in ports & pins. The other Probe signal pin attributes (active high/low
etc) may be configured as needed for the probe device being used on this pin.
- The Touch plate(s) must be connected to the pin for the mach Timing signal. The other
Timing signal pin attributes (active high/low etc) may be configured as needed for the
device(s) being used on this pin.

There are some restrictions that must be followed in order to use this “two signal” interface
approach:
1) The Mach Probe Signal and the Timing Signal must both be defined and enabled in the
Mach Ports & Pins dialog.
2) Both the Probe and Timing Signals must be on input pins.
3) The Probe and Timing signals must be defined on the same Port. This is crucial, as the
interfaces will not work correctly if the two signals are defined on pins that are on
separate ports.

For example: You can not use the Probe Signal on Pin 13 of Parallel port 1 and the timing
signal on pin 15 of parallel port 2.

Attempting to use multiple ports may (very likely will) result in machine crashes
during probing operations.

6.1.3.2.1 Technical Notes about Two Signal Interfaceing:
Timing signal usage:
The “two signal” implementation makes use of the Mach Timing input signal. The timing signal
was deprecated in mach is no longer used by Mach in the 3.43.xx series, however it is still present
in the ports & pins table. This made it a easy signal for MSM to repurpose and use as the touch
Plate input.

MachStdMill GUI impacts:
When using the standard one signal interface, all devices present the single Probe input signal to
mach and hence to MSM. Effectively all devices are “OR’ed” together and any device that is
triggered will cause an active probe input signal to mach. A convenient side effect of this is that
any device will cause the MSM Probe LEDs to turn on when any device is triggered, which makes
it easy to manually check the devices for connection and correct operation,

When using the “two signal” interface approach, the probe signal is the default input signal that
mach and MSM use. The Touch plate input (the mach Timing signal pin) is dynamically selected
during a probe operation and is used to “replace” the Probe signal input only when the touch plate
is in actual use for a probing operation that uses a touch plate.

This makes the Probe input the active input 99.9% of the time. Thus pushing on the probe will
toggle the MSM Probe LEDs. However, it is now effectively impossible to use the MSM probe
LEDs to test the touch plates – as the touch plate signal is only “connected thru Mach to MSM”
for brief periods during the course of a TP probe operation. This is an unavoidable consequence
of the two signal interface implementation.

BoB interactions:
Some break out boards have implemented the electronics required to accept mixed active high and
active low signals, combine them and feed the combined SINGLE input signal into mach as the
Probe signal (the PMDX 126 is an example of a breakout board which offers this features). In this
situation there are two wires, from two devices, connected to two screw terminals on the break out
board. HOWEVER, only one signal is provided as input into mach. This is a “one signal” (but two
pin) interface situation (not a two signal, two pin interface) as Mach (and MSM) are only using the
single Probe input signal.

Do not confuse this with the Two signal interface. The two signal interface also uses two wires
and two physical connections (pins), but it also presents two separate logical signals to mach (one
from each input pin).

Mach Version restriction:
The Two signal interface requires the use of a Mach script interface that is not present in a Mach
LockDown release prior to mach 3.43.66. MSM checks to see if the two signal interface is being
used and also checks the Mach version. If the combination is incompatible, a prominent warning is
displayed to the user when MSM starts. MSM allows Mach and itself to go ahead and startup (so
that the user can either use the Mach ports & pins dialog to rectify the conflict or update the
installed Mach release.
CAUTION: Ignoring the mach version warning is a very bad idea!!!

[charisbill]

Section 6.1.3.2 does not exist in the manual I downloaded from the site. The manual date is May 9, 2013. Is that the latest manual update or is there a later one somewhere to download?

Bill

[DaveCVI]

Uh oh,
t looks as if I forgot to update the separate copy on the production release download page - so it was older than the copy that is installed by the MSM installer. I have updated the file and the button will now give you rev 2.10 from July 12th. That has the section in it.

Dave

[charisbill]

Ahhh! That explains it. I don't have Adobe on the old XP machine that is running the router so I didn't link to the manual through MachStdMill. I used my laptop to download it from the web site. I'm looking forward to playing with the probe and touch plates this week. Thanks for the help and patience.

Bill