Detcon 880S-N4X - Manual (Page 8)

880-N4X
880-N4X Instruction Manual Rev. 0.0 Page 4 of 36
The touch panel acts as a master interface to the internally located PLC. As such, the touch panel polls the
PLC, which, in turn, polls the field devices for information. A wand is used on the screen to operate system
controls and/or move to additional screens.
A USB port (Figure 3) is located on the back of the display at the bottom. When a USB Drive (USB Memory
Stick) is installed, the display will automatically log to the drive where any alarms and/or faults have been
recorded by the PLC. The information is logged into a folder named ‘Log’ and named ‘Alarm_yymmdd.txt’
where yy is the year, mm is the month, and dd is the day. The files are written in text format.
2.3 Programmable Logic Controller
At the core of the Model 880 is the modular Programmable Logic Controller (PLC), which is designed to offer
maximum flexibility in system configuration (Figure 4). The PLC and all other electronic components are
mounted within the enclosure.
G
+
Direct
LOGIC
205
PWR
BATT
STOP
RUN
TERM
CPU
RUN
CPU
RELAY
CA
4
5
CB
4
5
0
1
2
3
0
1
2
3
4
5
7
6
1
3
2
0
D2-12TR
OUT RELAY
5-240VAC
1.5 50/60Hz
5-30VDC
5mA-1.5A
B
A 4
5
7
6
1
3
2
0
D2-08TR
OUT RELAY
7
3
6
2
5
1
4
0
C
C
5-240VAC
1A 50/60Hz
5-30VDC
5mA-1A
L
L
D2-DCM
DATA
COM
D2-DCM
DATA
COM
4
5
7
6
1
3
2
0
SPARE
Figure 4 Basic PLC
Installed in the PLC is the programmable Central Processing Unit (CPU), which processes all instructions,
data, and polls all field devices. The CPU utilizes flash memory to store the running program. All units are
shipped with firmware loaded and a lithium battery installed. The CPU has two communication ports. The
top RS232 port (Port 1) is the programming and interface for the touch display panel. The 15-pin bottom port
(Port 2) supports RS232 or RS422 and serves as I/O master for the RS-485 Modbus™ network.
The PLC contains an 8-channel and a 12-channel Relay Output Module. The 8-channel relay output module
controls the LED’s on the front panel of the unit, while the 12-channel relay output module controls the 12
10Amp relays used for customer supplied Alarm 1, Alarm 2, Alarm 3 and Fault circuits or annunciators. The
relays are labeled in ‘Banks’ as “ALARM 1”, “ALARM 2”, “ALARM 3”, and “FAULT”.
Remote Display and Auxiliary units utilize the two Data Communication Modules. The modules are used for
communication with the Remote Display, printers, and other external compatible devices.
2.4 Isolated Network Adapter
The Model 880 PLC uses an Isolated Network Adapter to interface devices on the RS-485 Modbus™ network.
The Isolated Network Adapter (Figure 5) converts RS-422/485 signals from sensors and other digital devices,
to an RS-232 signal that the main CPU can utilize.