York YK-EP B, Руководство по эксплуатации и техническому обслуживанию, Страница: 207 / 226

SECTION 5 - SERVICE
JOHNSON CONTROLS
207
FORM 160.87-OM1
ISSUE DATE: 8/24/2018
5
KEYPAD INTERFACE
The keypad is read via J18. The keypad is a matrix
of conductors arranged in rows and columns (Refer to
Form 160.54-M1
). There are 4 rows and 8 columns.
When a key is pressed, the conductors are pressed to-
gether at that point, creating continuity between the
row conductor and the column conductor. The keypad
is read by applying a logic low to a row while leaving
+5VDC pull-up on all other rows. The microprocessor
then reads the 8 columns. If any column has a logic low
on it, the key corresponding to that coordinate (row,
column) is being pressed. The microprocessor reads
the entire keypad by repeating this routine beginning
with row 1 and ending with row 4. The entire keypad is
continually read while the Control Center is powered.
CM-2 BOARD OR STYLE A SOLID STATE
STARTER INTERFACE
The microboard retrieves certain operating parameters
(via J10) from the compressor motor starter control
board (CM-2 Current Board for Electro-Mechanical
Starter or Style A Solid State Starter Logic Board). Re-
fer to Form 160.54-M1 for a detailed explanation of
each board. Both boards contain an 8 channel multi-
plexer. The microprocessor sequentially and continu-
ally reads channels 0 through 7. It reads each channel
by applying a 3-bit binary address to the multiplexer.
A 0 to 5VDC analog value is re-turned from each chan-
nel. The function of each is in the
Table 12 on Page
207 .
The microprocessor determines which board, and
therefore which starter is present, by the value returned
from channel 0. Since channels 0 through 6 are ground-
ed, the CM-2 board returns a 0VDC value. The Solid
State Starter Logic Board returns a value greater than
0.41VDC to +5VDC. If the value is less than 0.4VDC,
it indicates the starter is an Electro-mechanical (EM)
starter and the microprocessor then reads channel 7 to
retrieve the peak motor current value. A value greater
than 0.4VDC indicates the starter is an A style Solid
State Starter and the microprocessor reads channels 1
through 7.
In the Solid State Starter, channel 0 indicates the
starter size (model) and voltmeter range (300VAC or
600VAC). Channel 1 is a hardware generated 100%
FLA (prevents pre-rotation vanes from further open-
ing) or 104% FLA (closes pre-rotation vanes until mo-
tor current is less than 102%) current limit override
command that overrides normal Pro-rotation Vanes
control. Channels 2 through 4 are analog voltages that
represent phase A, B and C motor current. The highest
phase is Channels 5 through 7 are analog voltages that
represent phase A, B and C Line Voltage. The data for
each channel is shown on the below.
TABLE 12 - MULTIPLEXER CHANNELS
0 1 2 3 4 5 6 7
CM-2 GND GND GND GND GND GND GND
Peak Motor
Current
(%FLA)
STYLE A
SOLID STATE
STARTER
Starter
model/
voltmeter
range
Current
limit
command
Phase C
motor
current
Phase B
motor
current
Phase A
motor
current
Phase A
line
voltage
Phase B
line
voltage
Phase C
line
voltage