Interface between max. 3 absolute-value sensors (SSI) and the CPU
For provision of the displacement encoder values for further processing in STEP 7 programs
Enables direct response of controller to encoder values in moving systems
Displacement measuring systems and precut/preassembled cables for counting and positioning functions are available under SIMODRIVE Sensor or Motion Connect 500.
The SM 338 POS input module can be used as an interface between up to 3 absolute encoders and the S7-300 CPU. It makes position-encoder values available for subsequent processing in the control and provides the conditions for the control to respond directly to encoder values in systems under motion.
The POS input module is equipped with:
3 SSI encoder inputs
2 digital inputs
24 V DC encoder supply
The POS input module converts SSI position-encoder signals from the process into digital values for the S7-300.
You can select either:
Cyclic encoder-value sensing
Encoder-value sensing isochronous to the PROFIBUS DP cycle.
The recorded values can be processed directly in the STEP 7 program so that a direct reaction is possible to encoder values in moving systems.
In addition, the SSI encoder states can be frozen via two digital inputs of the module. This permits further time-critical applications in the sector of position detection.
SIMATIC S7-300, SIGNAL. MODULE
Load voltage L+
● Rated value (DC)
● permissible range, lower limit (DC)
● permissible range, upper limit (DC)
from load voltage L+ (without load), max.
from backplane bus 5 V DC, max.
24 V encoder supply
● 24 V
Yes; L+ (-0.8 V)
● Output current, max.
Power loss, typ.
● for signal “0”
-3 to +5V
● for signal “1”
11 to 30.2 V
● for signal “0”, max. (permissible quiescent current)
● for signal “1”, typ.
Input delay (for rated value of input voltage)
for standard inputs
— at “0” to “1”, min.
● shielded, max.
Number of connectable encoders, max.
● Absolute encoder (SSI)
● 2-wire sensor
Encoder signals, absolute encoder (SSI)
● Cable length, shielded, max.
320 m; 320 m at 125 kHz; 160 m at 250 kHz; 60 m at 500 kHz; 20 m at 1 MHz