Optional 4-20Ma Analog Output Board; Revision - Honeywell HA71 Technical Manual

HA71 Digital Gas Controller

3.1.6 Optional 4-20mA Analog Output Board

An optional 10 bit 4-20mA analog output board, shown in Figure 3-7,
may be connected to the I 2 C bus. Each channel's output will transmit
4mA for 0% readings and 20mA for 100% readings. Loop drive
capability depends upon the level of the HA71's primary DC power
supply. With at least 20 volts DC primary power they are capable of
driving 20mA through a 750 ohm load. Outputs are self powered and
DC power should not be provided by the receiving device.
Note
This PCB requires nominal 24VDC power be connected to
TB2 terminals 1 & 2 as shown in Figure 3-6. Suitable power is
available from the HA71 Main I/O board's TB2 terminal 10 &
12 (see Figure 3-1).
Since the PCB has 8 channels, two are required for 16 channel
applications. JP1 configures the outputs for channels groups 1-8 or
9-16.
HA71 Technical Manual
D2
Q16
Q15
Q14
Q13
Q12
Q11
Q10
Q8
Q6
Q4
Q2
24 VDC power for output
current loops must be
Connect to
supplied through TB2. "DC OUT"
Connect to main I/O PCB on I/O PCB
terminals 10 & 12 of TB2.
TB2
+ -
24 VDC
INPUT
Figure 3-7. 8 Channel 4-20mA Output Option 10-0167
3-8
D1 U9
U10
Q17
JP1 determines if this 8 channel
U8
Analog Output PCB provides
outputs for CH's 1-8 or 9-16.
2 PCB assemblies are required
J1
for 16 channels.
C2
J1 & J2 are interchangable I2C
C4
connectors used to add option
PCB assemblies to the HA71.
J2
Q9
TP1
C1
Ref. Adj. allows trimming voltage
U11
on TP1. 2.048 volts provides
C7
Q7
20mA (+1%) outputs with 100%
of full scale readings.
R26
Q5
CR1
C3
C6
Q3
ST-71 mA OUTPUT BOARD
Assy # 10-0167
PCB # 0010-1121 Rev 0
Q1
Milliamp
Outputs
Low's
LO LO LO LO LO LO LO LO
TB1
High's
HI HI HI HI HI HI HI HI

Revision 3 (04/08)