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3.6 Activating the Open Collector Output
In addition to the beeper, the MMI-2xx series also contains an Open Collector
Output. To use the Open Collector Output (O.C.), a constant must be sent to a
defined register in the PLC. The Open Collector Output is a small transistor device
that can be turned on to trip an external relay that could sound an external sound-
ing device, etc. Please observe the current limits on the Open Collector Output, as
described in the Specifications in Section 5.0.
For example, to turn on the O.C. Output, a constant that turns on Bit 11 and Bit 12
should be sent to the LED R1. That means in Binary, a constant of
0000110000000000 may be used. This is equivalent to C00 in Hex or 3072 in
Decimal. To shut off the O.C. Output, those bits should be turned off.
The O.C. Output may also be set up to activate every time a key is depressed.
This allows for user feedback of key presses in a noisy environment, if the O.C.
Output is hooked to a local alarm. This is done in the Windows
based
MMISoft
setup software in the Edit|Setup menu. Clicking on the check box next to Open
Collector adds a check mark that enables the O.C. Output and causes it to
activate every time a key is pressed. Clicking on the box again removes the check
mark and disables the O.C. Output. Note that the O.C. Output may still be
activated by using its control bits as described in the previous paragraph.
3.7 Using the Keypad Download
The MMI-2xx series also allows the keypad to turn on a bit in a specific register in
the PLC when a key is depressed. When keypad downloading is enabled and a
key is pressed, the key's corresponding bit is turned ON in the PLC. When the
key is released, the bit is restored to the OFF state.
Depending on the LED register chosen, the keypad status is downloaded to the
second and third registers directly after the LED register. These registers are
referred to as the LED R2 and LED R3 under Keypad Download in
the Specifications in Section 5.0. See that section for the key to bit relationship.
To enable keypad download, use the Windows
based
MMISoft
setup software
and select the Edit|Setup menu. Clicking on the check box next to Download
Keypad adds a check mark that enables the keypad to be downloaded and causes
it to turn a bit ON in the PLC every time a key is pressed. Clicking on the box
again removes the check mark and disables the keypad download.
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