Honeywell HA71, Technical Manual

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HA71 Digital Gas Controller
Revision 3 (04/08)
HA71 Technical Manual 3-3
3.1 Input / Output Optional PCBs
Telephone style RJ11 connections are used to add optional 8 channel
analog and digital I/O. A screen appears briefly after power up
indicating what options are connected and for which channels. This
information is also available from the Diagnostics Mode described in
Section 4 .
PRESS NEXT KEY TO EXIT
ANALOG
INPUT
1-8
FOUND
ANALOG
INPUT
9-16
FOUND
ANALOG
OUTPUT
1-8
FOUND
ALARM2
INPUT
9-16
FOUND
ALARM2
RELAY
1-8
FOUND
ANALOG
OUTPUT
9-16
FOUND
Figure 3-2. Optional PCB Display
3.1.1 Optional Analog Input PCB
Many transmitters or sensors have analog output signals and the 12
bit Analog Input PCB, shown in Figure 3-3, is available to accept these.
TB1, with 24 positions, offers 3 terminals per channel for distributing
power and receiving analog inputs. These are EXC and HI / LO inputs.
TB2, with only two positions, is for connecting the power supply for
powering external transmitters. Precision 100 ohm resistors (R1-R8)
between each channel’s IN LO and IN HI terminals are socketed
termination resistors for 4-20mA inputs. These may be removed if
voltage inputs are to be applied.
EXC and IN LO terminals are bussed together internally. EXC terminals
are tied directly to TB2-1 (+) and IN LO terminals are tied to TB2-2
(-). Bussing allows transmitter power to be brought into the system at
a single point (TB2) and distributed back out at each channel’s EXC
/ IN LO terminals to simplify field wiring. Figure 3-3 includes typical
wiring to 2 and 3 wire 4-20mA transmitters.
JP1 determines if the 8 analog inputs are applied to channels 1-8
or channels 9-16. Connecting more than 8 analog inputs requires
2 PCB’s with one’s JP1 set for channels 1-8 and the other set for
channels 9-16.
R2
R1
ANALOG INPUTS
R3
R4
R7
R6
R5
+EXC-
DC PWR
TB2
R8
JP1
ST-71 ANALOG INPUT BOARD
0010-1115 ASSY# 10-0158
J2
J1
J1 & J2 are interchangable I2C
connectors used to add option
PCB assemblies to the HA71.
JP1 determines if this 8 channel
Analog Input PCB provides inputs
for CH’s 1-8 or 9-16. 2 PCB
assemblies are required for 16
channels.
Socketed precision resistors R1-R8
are 100 ohm terminations for 4-20mA
inputs. 0-2 VDC voltage inputs may
be accepted by removing resistor.
CH1/9
EXC HI
CH7/15
HI EXC
CH3/11
EXC LO HI LO
CH5/13
LO HI EXC LO
CH2/10
HI EXC
CH8/16 CH4/12
EXC LO HI C X E O L
CH6/14
EXC LO O L I H HI
EXC LO HI
2 Wire 4-20mA
Transmitter
+Pwr Sig
3 Wire 4-20mA
Transmitter
EXC LO HI
+Pwr
Sig Com Typical 2 & 3 wire 4-20mA
transmitter wiring (connect
correct power, 24VDC or
other, to TB2).
CH # (1-8) CH # (1-8)
TB2 is for powering bulk power
to transmitters or other input
devices. EXC+ is wired internally
to channel “EXCs” and
EXC-to-channel “LOs”.
Figure 3-3. 8 Channel Analog Input Option 10-0158