Mutually Exclusive; Defining Momentary Mutually Exclusive - AMX AXCESS CONTROL SYSTEM PROGRAM Instruction Manual

Channel Characteristics
button is released), the channel does not go back to OFF (like a momentary channel), it stays ON. It
only returns to OFF when the channel is reactivated by a TO keyword. As a result, the status of a
latching channel reflects the true ON/OFF state of the channel.
In your program, RELAY is already defined as device number 4 and SYS_POWER is defined as a
constant having the value 3. Using these two values together as device-channel
[RELAY,SYS_POWER] gives you a relay to use for your system's power control. You will need to
make this relay latching so that it stays on after you release the Touch Panel button. Also, your
drape motor needs latched relays to operate. Here are the definitions:
DEFINE_LATCHING
[RELAY,SYSTEM_POWER]
If you have a series of consecutive channels to be defined, you can use double periods (..) as a
shortcut. The use of double periods will specify a range of channels between the first and last
channel. For example, if the lights in your system need latched relays to operate, instead of defining
each one right after the other, follow this example:
[LIGHTS,LIGHT_FULL]..[LIGHTS,LIGHT_OFF]
In your DEFINE_CONSTANT section, you defined these constants as 1 through 4, so this will
make relays 1 through 4 on the LIGHTS card (card 5) latching.

Mutually Exclusive

Channels can also be defined as mutually exclusive. A mutually exclusive group is a set of channels
in which only one channel of the set can be turned on at a time. The three kinds of mutually
exclusive channels are momentary, latching, and toggling. They are each described below:

Defining momentary mutually exclusive

When a channel is turned on in a momentary mutually exclusive set, it activates its physical output
as long as the button is pressed. When the button is released, the physical output stops. The status,
however, does not work in the same manner. Even after the physical output stops, the status still
indicates that the channel is on until another channel in the mutually exclusive set is activated. The
status is on to let you know which channel in the set was last activated. This is sometimes called last
button pressed feedback.
Be sure to find out which devices need mutually exclusive channels. Do not wait until
you test the program, as you could damage some devices.
When a channel or variable in this set is activated, all the other members of the set are turned off
beforehand. This is called break before make logic. This prevents accidental activation of more than
one channel at the same time, which could cause serious damage to some devices.
For example, consider the drape and screen channels of the device RELAY. Since you cannot open
and close a drape all at once, and you cannot raise a screen and lower it at the same time, only one
channel can be turned on at any time. They must be defined as mutually exclusive. When
SCREEN_UP is activated, the SCREEN_DOWN channel is turned off and SCREEN_UP turns on.
The corresponding SCREEN_UP status stays on even though the relay is de-energized when the
button is released. When SCREEN_DOWN is activated, SCREEN_UP is turned off. The
SCREEN_DOWN status is now the only status turned on.
20 Axcess Programming Language