+24V dc
MPCE 1
SO1
MPCE1
Safety Input
Device
EDM
Safety Controller
MPCE 2
MPCE2
Single-channel EDM used to monitor both MPCE
feedback signals. If one or both channels do not
close, the system enters a lockout mode.
Figure 69. One-channel EDM hookup
+24V dc
MPCE 1
SO1
MPCE1
Safety Input
Device
EDM EDM
Safety Controller
MPCE 2
MPCE2
Dual-channel EDM used to monitor both
MPCE feedback signals. If the channels are
not in the same state, the system enters a
Lockout mode.
Figure 70. Two-channel EDM hookup
External Device Monitoring EDM is a way to check the operation of dual channel final switching
devices or machine primary control elements. The force guided N.C. monitoring contacts of the
FSD or MPCE are used as an input to detect a “stuck on” fault condition and will prevent the safety
controller outputs from turning On.
External Device
Monitoring
250 ms
250 ms
Don’t Care
Don’t Care
Closed
Open
SO1
EDM
Figure 71. Timing logic: One-channel EDM status, with respect to Safety Output
For two-channel EDM, as shown below, both channels must be closed before the Safety Output(s) turn On.
XS/SC26-2 Safety Controller
91