420 Plus Installation Manual - Installation
9
2.3.4
Load Cells
To attach cable from a load cell or junction box,
remove connector J1 from the board. The connector
plugs into a header on the bo ard as sho wn in
Figure 2-4 7.
Using one of the 6-position connectors, provided in
the parts kit, wire the load cell cable from the load cell
or junction box to connector J1 on the CPU board (See
Figure 2-4 7). If using six-wire load cell cable (with
sense wires), remove jumpers JP1 and JP2 before
reinstalling connector J1 (see Figure 2-4). For
four-wire installation, leave jumpers JP1 and JP2 on.
When connections are complete, reinstall connector J1
onto the header so that it snaps securely into place.
Use two cable ties to secure the load cell cable to the
inside of the enclosure.
Use grounding procedures described in
Section 2.3.1 on page 6
For 6-wire connections, remove jumpers
JP1 and JP2
For 4-wire connections, leave jumpers JP1
and JP2 on
2.3.5
Serial Communications
Using one of the six-position connectors, provided in
the parts kit, wire the serial communications cables to
J4. Connector J3 provides connections for the EDP/
RS-232 port. Connect communications cables to
connectors J3 and J4 as shown in Table 2-3.
Once cables are attached, reconnect J3 and J4 to the
headers on the board (see Figure 2-4). Use cable ties
to secure serial cables to the inside of the enclosure.
T h e E D P p o r t s u p p o r t s f u l l d u p l e x R S - 2 3 2
communications only; the serial port provides either
active 20 mA output or duplex RS-232 transmission.
Both ports are configured using the SERIAL menu.
See Section 3.0 on page 1 4 for configuration
information.
2.3.6
Digital I/O
Digital inputs can be set to provide several indicator
functions, including all keypad functions. The inputs
are active (on) with low voltage (0 VDC) and can be
driven by TTL or 5V logic without additional
hardware. Use the DIG IN menu to configure the
digital inputs. LED’s on the CPU board light when
digital inputs are active.
Digital outputs are typically used to control relays that
drive other equipment. Outputs are designed to sink
not source, switching current. Each output is a
normally open connector circuit, capable of sinking
250 mA when active. Digital outputs are wired to
switch relays when the digital output is active (low, 0
VDC) with reference to 5 VDC supply. LEDs on the
CPU board light when the digital outputs are active.
J1 Pin
Function
1
+SIG
2
–SIG
3
+SENSE
4
–SENSE
5
+EXC
6
–EXC
Table 2-2. J1 Pin Assignments
Note
Port
Connector
Pin
Label
EDP/RS-232
J3
1
TxD
2
RxD
3
Gnd
Serial Port
J4
1
TxD
2
RxD
3
Gnd
4
20mA+
5
20mA–
6
Gnd
Table 2-3. J3 and J4 Pin Assignments
Port
Connector
Pin
Label
Digital Input
J2
1
DI 1
2
DI 2
3
Gnd
Digital
Output
J6
1
Gnd
2
DO 1
3
DO 2
4
+5V
Table 2-4. J2 and J6 Pin Assignments
