Omron NE1A Series Manual page 160

Command Reference: Function Blocks
Sequential Muting (Forward Direction)
In this example, four Through-beam Photoelectric Sensors are set up as the
sensors with intersecting detection zones.
Use this configuration when the length of the workpiece being transported is
longer than a fixed length.
Block Diagram
V V
Workpiece
L
MS11: Muting sensor connected to Muting Signal 11
MS12: Muting sensor connected to Muting Signal 12
MS21: Muting sensor connected to Muting Signal 21
MS22: Muting sensor connected to Muting Signal 22
Muting Sequence
1. In the block diagram above, the light is not interrupted between MS11,
MS12, MS21, and MS22 and the light curtain, so the Output Enable signal
is ON.
2. As the workpiece moves to the right and MS11 and MS12 go ON in order,
muting is enabled, and the Muting Status goes ON.
3. As the workpiece continues advancing, the Output Enable signal is kept
ON even if the light curtain is obstructed.
4. As the workpiece continues advancing, light from MS21 is no longer inter-
rupted by the workpiece, the muting status is cleared, and the Muting Sta-
tus goes OFF.
Setup Distances
The following formulae show the minimum distances of D2 and D3 required
for the muting sensors to provide effective muting function operation:
Formula 3: D2 < L
Formula 4: D3 < L
L: Length of the workpiece
The following formula shows the maximum distance of d2 required for the
muting sensors to provide effective muting function operation:
Formula 5: V × T1min < d2 < V × T1max
V: Transit speed of the workpiece
T1min: NEA1-series Controller cycle time
T1max: Synchronization time setting time
The default setting is 3 s.
Light curtain
MS11 MS12 MS21
MS11 MS12 MS21
d2
D2
D3
Section 6-5
MS22
MS22
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