7800 Controller - User Manual - Scott Safety

Model 7800 Users Manual
Revision E
ANALOG
INPUT
1- 8
FOUND
ANALOG
INPUT
9- 16
FOUND
ANALOG
OUT PUT
1- 8
FOUND
ANALOG
OUT PUT
9- 16
FOUND
ALARM2
Re l a y
1- 8
FOUND
AL ARM2
INPUT
9- 16
FOUND
PRESS NEXT KEY TO EXIT
Figure 3.2
3.1.1 OPTIONAL ANALOG INPUT PCB 093-0268
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 & 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.
Scott Safety
22
087-0021 Rev F