Banner MAXI-BEAM Series - Manual (Page 12)

Photoelectric Latch with
Manual Reset
1CR relay will latch ON whenever the 2-wire MAXI-
BEAM output is energized. 1CR is reset when the
normally-closed pushbutton switch is pressed.
2-wire MAXI-BEAMs in Parallel
Multiple 2-wire MAXI-BEAMs may be wired together in
parallel to a load for "OR" or "NAND" logic functions.
When sensors are wired in parallel, the off-state leakage
current through the load is equal to the sum of the leakage
currents of the individual sensors. Consequently, loads
with high resistance like small relays and electronic cir-
cuits may require artificial load resistors.
MAXI-BEAM sensors have a 100 millisecond power-up
delay for protection against false outputs. When 2-wire
MAXI-BEAMs are wired together in parallel, any power
block which has an energized output will rob all other 2-
wire power blocks of the voltage needed to operate the
sensor. When the energized output drops, there will be a
0.1 second delay before any other MAXI-BEAM can
energize. As a result, the load may momentarily drop out.
2-wire MAXI-BEAM sensors cannot wire in series with
other 2-wire sensors. If series connection of 2-wire AC
sensors is required, consider models within the VALU-
BEAM or MINI-BEAM sensor families. 4-wire ac power
blocks can wire in series (see RPBA, RPBB).
V ac
(See Specifications)
4
3
1
2
RESET
L1 L2
1CR
1CR
LATCH R2PBA
R2PBB
4
3
1
2
V ac
(See Specifications)
L 1
2
L
R2PBA
R2PBB
LOAD
L1 L2
V ac
(See Specifications)
LOAD 4
3
1
2
R2PBA
R2PBB
Basic 2-wire Hookup
MAXI-BEAM sensors using power block R2PBA or R2PBB wire in
series with an appropriate load. This combination, in turn, wires directly
across the ac line. A 2-wire sensor may be connected exactly like a
mechanical limit switch.
The MAXI-BEAM remains powered when the load is OFF by a residual
current which flows through the load. This off-state leakage current is
always less than 1.7 milliamps. The effect of this leakage current
depends upon the characteristics of the load. The voltage which appears
across the load in the OFF state is equal to the leakage current of the
sensor multiplied by the resistance of the load:
V (off) = 1.7mA x R(load).
If this resultant OFF state voltage is less than the guaranteed turn-off
voltage of the load, then the interface is direct. If the OFF state voltage
causes the load to stay ON, then an artificial load resistor must be
connected in parallel with the load to lower its effective resistance. Most
loads, including most programmable logic controller (PLC) inputs, will
interface to 2-wire sensors with 1.7mA leakage current, without the need
for an artificial load resistor.
There is no polarity requirement. Either wire may be connected to
terminal #3, and the other to terminal #4.
CAUTION: all components of a MAXI-BEAM 2-wire sensor assembly
will be destroyed if the load becomes a short circuit.
Hookup of 2-wire MAXI-BEAMs to a Programmable Logic Controller
(PLC)
2-wire MAXI-BEAM sensors may be wired in
parallel with mechanical switch or relay con-
tacts. The load will energize when either a
contact closes or the sensor output is energized.
When a contact is closed, it shunts the operating
current away from the MAXI-BEAM. As a
result, when all of the contacts open, the
MAXI-BEAMs 0.1 second power-up delay
may cause a momentary drop-out of the load.
2-wire MAXI-BEAMs with
Series Contacts 2-wire MAXI-BEAMs with
Parallel Contacts
MAXI-BEAM 2-wire sensors operate with
low (1.7mA) off-state leakage current. As a
result, they will interface directly to most
PLCs without the need for an artificial load
resistor. If the off-state voltage (1.7mA x
input resistance of PLC) is higher than the
PLC sensing threshold, install a 10K
Ω to
15K
Ω
, 5 watt resistor for each 2-wire sensor.
The resistor connects between the input ter-
minal and ac neutral.
If you have a question on hookup to a spe-
cific brand of PLC, contact the Banner Ap-
plications Department during normal busi-
ness hours.
R2PBA
R2PBB
4
3
1
2
4
3
1
2
LOAD
V ac
(See Specifications)
L 1 2 L
R2PBA
R2PBB
4
3
1
2
V ac
(See Specifications)
L 1
2
L
R2PBA
R2PBB
LOAD
When 2-wire MAXI-BEAM sensors are con-
nected in series with mechanical switch or relay
contacts, the sensor will receive power to oper-
ate only when all of the contacts are closed. The
false-pulse protection circuit of the MAXI-
BEAM will cause a 0.1 second delay between
the time that the last contact closes and the time
that the load can energize.
12
4
3
1
2
V ac
(See Specifications)
L 1
2
L
Hookup
typical
for all
8 inputs
AC "hot" AC neutral
R2PBA
R2PBB
I
N
P
U
T
S
P
r
o
g.
C
t
r
l.
neutral
1
2
3
4
5
6
7
8
MAXI-BEAM
Power Blocks and Wiring Base
Hookup Diagrams for R2PBA and R2PBB Power Blocks