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The Input Buffers latch and hold the Dig i tal In puts
(Microboard J19) from the I/O Board and the col umn
out puts from the keypad until read by the Mi cro.
115VAC dig i tal inputs from relay contacts and ex ter nal
devices are con vert ed to +5VDC logic levels by the I/O
Board prior to ap pli ca tion to the Microboard. Sim i lar ly,
the Keypad column outputs are held and read by the
Micro as de scribed above.
To provide flexibility for future Analog In puts (to
Microboard J7), 2 analog inputs can be confi gured for
either 0-10VDC, 2-10VDC, 0-20mA, or 4-20mA Trans-
duc er or Ther mistor in puts using Program Jump ers JP21
through JP24. The po si tion of the jumper de ter mines
which type of input can be con nect ed. Refer to Fig. 12
and Table 1, "Pro gram Jumpers".
These inputs are for future YORK Fac-
to ry ex pan sion use only. They are not
gen er al ap pli ca tion spare in puts that
will sup port arbitrarily in stalled de-
vic es. Devices CAN NOT be con nect ed
to these in puts un til the pro gram has
been mod i fi ed to read and process the
in put. Un less YORK doc u men ta tion
shows a de vice con nect ed to the in put
with a de fi ned func tion, the in put can-
not be used.
Remote Leaving Chilled Liquid Tem per a ture and Cur-
rent Limit Setpoints can be applied to the RS-232 se ri al
port J2 via the Microgateway (ref. Fig. 11) or directly to
the Microboard at J22 (ref. Fig. 12). The inputs at J22
can be con fi g ured with Program Jump ers JP23 and JP24
to ac cept these inputs in either 0-10VDC, 2-10VDC,
0-20mA or 4-20mA form. Refer to Table 1 for Pro gram
Jump er con fi g u ra tions.
The Microboard receives 3 supply voltages (Microboard
J1) from the Power Supply; +12VDC, -12VDC, +5VDC
and Ground. The -12VDC and +12VDC are used directly
by various circuits. The +12VDC and +5VDC are input
to Voltage Regulators to derive oth er reg u lat ed volt-
ag es. The +5VDC (fused by 5 Amp fuse F1 on rev "E"
and later boards) is input to a +3.3VDC reg u la tor. The
output is a 3.3VDC regulated voltage. The +12VDC
(fused by 5 Amp fuse F2 on rev "E" and later boards)
is in put to a 5VDC regulator. The output of this reg u -
la tor pow ers only the Analog circuits. This in cludes the
YORK INTERNATIONAL
MUX, A/D con vert er, CM-2 module, Mod "A" Solid
State Start er Logic Board, Trans duc ers and Ther mistors.
As de pict ed on the Microboard fi gure, these volt ag es can
be monitored at Test Posts TP1 through TP6.
The Microboard is equipped with 5 Serial Data Ports
(ref. Fig. 11). Connector J2 is shared with both COM
1 and COM 4B. Each Port is dedicated for a specifi c
func tion as follows:
a. COM 1 (J2) - RS-232. Printer.
b. COM 2 (J13) - RS-232. Not Used.
c. COM 3 (J12) - RS-485. Optional I/O.
d. COM 4 (4A-J11), (4B-J2) - This port is actually
two ports. However, they cannot be used si mul ta -
neous ly; only one of these ports can be con nect ed
to a device at a time. The position of Microboard
Program Jump er J27 determines which port can be
used (refer to Table 1). COM 4A (J11) is an RS-485
port that is used for Multi-Unit Com mu ni ca tions.
COM 4B (J2) is an RS-232 port that is used for
MicroGateway.
e.) COM 5 (J15) – Opto-coupled TX/RX. VSD Adap-
tive Capacity Control board.
COM 1 is connected directly to the Micro. COM 2
through 5 are connected directly to the UART (Uni ver sal
Asynchronous Receive Transmit). The UART con verts
the parallel data to serial form for trans mis sion to the
peripheral device and converts the in com ing serial data
to parallel form for use by the Micro. It also gen er ates
and processes control signals for the Modem com-
mu ni ca tions (DTR, CTS, DSR, RTS). Un der Pro gram
control, the Mi cro instructs the UART of the de sired
data trans mis sion Baud rate. A crystal os cil la tor pro vides
the frequency reference. Each port is equipped with two
LED'S; a red one indicates when data is being trans-
mitted to the remote device and a green one in di cates
when data is being received from the re mote de vice.
The RS-232 output voltages are in dus try standard +3
to +15VDC, with +9VDC typical. The RS-485 out put
voltages are industry standard +1.5 to +5VDC, with
+2.5VDC typical. The TX/RX sig nals of COM 5 are 0
and +5VDC logic level sig nals. A loopback diagnostic
test can be performed on each se ri al port. This test per-
mits verifi cation of the data trans mit ted from the serial
port. Refer to the "Diagnostics" sec tion of this book for
de tails of these tests.
FORM 160.54-M1(503)
3
23
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