Detcon 880S-N4X - Manual (Page 12)

880-N4X
880-N4X Instruction Manual Rev. 0.0 Page 8 of 36
A B +
RS-485 VDC
Primary Out
Figure 8 Typical RS-485 connections
Analog Connections
3. For Analog Units (880A), communication is accomplished by using Detcon DA4 modules and the RS-
485 Modbus™. The 4-20mA sensors are directly connected to the DA4 modules, while the DA4
modules are connected via the RS-485 Modbus™ to the 880 PLC (Figure 9). All DA4’s are externally
mounted and require an external power source. The correct setup of the DA4’s is covered in Section
4.3 880 Setup.
WARNING: If the 24VDC output is used to power external components the output is to be restricted
to no more than 4Amps maximum (96 Watts). This equates to 7 DA4 Modules with 28 attached
sensors and/or field devices. Care should be taken to insure that the total current of equipment
utilizing this power does not exceed this 4Amp rating, as this may cause detrimental damage to the
unit and will void the warranty. An External Power Source should be used to power any and all
components that exceed this rating.
4-20mA
INPUT
COMM
M
S
D
L
S
D
Typical Sensors
RS-485 to 880
Sensor 2
Sensor 1
Sensor 3
Sensor 4
Figure 9 Typical Analog Sensor Wiring
4. Connect external annunciators to the relay terminals provided in the enclosure. The Alarm Relays are
set up in banks (BANK 1, BANK 2, and BANK 3). Each bank consists of a set of relays labeled
“FLT” (Fault), “ALM1” (Alarm 1), “ALM2” (Alarm 2), and “ALM3” (Alarm 3). Each relay has a set
of dry contacts labeled “12-COM” Common, “11-NC” Normally Closed, and “14-NO” Normally
Open (Figure 10). Wire annunciators to the appropriate bank and alarm/fault relay.