Allen-Bradley Guardmaster - Page 75

Rockwell Automation Publication 440R-UM013E-EN-P - March 2017 75
Troubleshooting Chapter 11
EM or EMD expansion relays have both SWS input and output signals. You
must connect a wire to L12. Your application requirements determine whether
L11 is used.
Figure 71
shows an example of an SWS connection. Note the L11 terminal
(which is the SWS output) can be connected to multiple L12 terminals (SWS
input), but the L12 terminal cannot be connected to multiple L11 terminals.
Figure 71 - Example SWS Connections
Figure 72 shows the characteristics of SWS signal when it is active. It starts
with a 1 ms pulse, followed 700 µs later by a 500 µs pulse. This waveform is
repeated every 4 ms. When inactive, the SWS is 0V.
Figure 72 - SWS Waveform
When the signal is active, use a digital multimeter to measure the voltage. The
digital multimeter shows 8…9V.
If a fault occurs with either an SWS input or SWS output, then that circuit is
held high. If a digital multimeter reads a voltage measurement of approximately
21V, the signal is high. The PWR/Fault status indicator flashes red five times.
TIP For long wire runs of the SWS signal, a shielded cable may be necessary to
help prevent nuisance faults from electromagnetic and motor noise.
DI
L12 L11
A1
A2
+24V DC +24V DC
24V DC Com (must have common reference)
CI or SI
L11
A1
A2
EM
L12 L11
A1
A2
DIS
L12 L11
A1
A2
+24V DC
SWS SWS
SWS
+24V DC
EMD
L12 L11
A1
A2
+24V DC
L11 and L12
Terminals
24V
0V
10 1.7 2.2 4ms