Relay Output Circuits - Siemens SIMATIC S7 Functional Safety Manual

Model
Off delay time
Behavior on RUN to STOP
Number of outputs on simultaneously
Parallel connection of 2 outputs
Control of a digital input
Switching frequency:
With resistive load
•
With inductive load in accordance with IEC 60947-5-1,
•
DC13
With inductive load in accordance with IEC 60947-5-1,
•
AC15
Inductive load in accordance with UL 508
•
Cable length (meters)
Reverse polarity protection
A.3.4.4

Relay output circuits

The SM 1226 F DQ 2 x Relay has two output channels (F-DQ a.0 and F-DQ a.1). Each
channel includes two circuits that switch mechanically-linked contacts at the same time.
Each circuit has two contacts in series controlled by independent relay coils. Opening and
closing of the series contacts in each circuit is sequenced to avoid common wear-out
failures.
Output channel a.0: Two circuits controlled as one process output channel
Refer to the isolation description in the SM 1226 F-DQ 2 x Relay (Page 185) specifications, Digital
outputs table.
S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA
A.3 Fail-Safe signal module (SM) technical specifications
SM 1226 F-DQ 2 x Relay
Typically 16 ms to first series contact open, second contact
opens approximately 40 ms later.
Only 0 (OFF) is allowed.
2
Allowed for redundant availability. Do not exceed single relay
load rating.
With 24 VDC SELV supply
2 Hz, maximum
0.1 Hz, maximum
2 Hz, maximum
Pilot Duty B300, R300
200 m shielded
•
200 m unshielded
•
No
Technical specifications
187