The output interfaces of incremental encoders or pulse generators are:
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RS 422/485 standard output, two push-pull outputs, complemented by the signal,
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5 V Totem pole output, two complementary push-pull outputs.
Absolute SSI serial encoders have a standardized RS 485 interface for clock and data signals.
We recommend an encoder with opto type "CLOCK" signal input stage. Different types of encoders can be connected onto the same module. For example, an incremental encoder on channel 0 and an absolute SII encoder on channel 1.
The module is designed to supply encoders with 5 V or 24 V. Mixing supply voltages is possible on all module channels.
Incremental encoders usually have a 5 V supply.
Absolute SSI encoders have a 24 V (10/30 V) supply.
5 V encoder supply: maximum drop in voltage.
In this case there is reason for taking the on-line voltage drop into account. This drop depends on cable length and encoder consumption for a given wire gauge.
Example for a 100m-long cable:
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Section of the wire
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Drop in voltage for a 100m-long cable
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Encoder consumption
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50 mA
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100 mA
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150 mA
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200 mA
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Gauge 28 = 0.08mm2
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1.1 V
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2.2 V
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3.3 V
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4.4 V
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Gauge 22 = 0.34mm2
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0.25 V
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0.5 V
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0.75 V
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1 V
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0.5 mm2
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0.17 V
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0.34 V
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0.51 V
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0.68 V
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1 mm2
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0.09 V
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0.17 V
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0.24 V
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0.34 V
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24 V encoder supply.
This type of encoder is recommended, because it does not need a precise supply (10 V/30 V). When there is a 24 V supply, these encoders make it possible to have a very large cable, which makes the voltage drop in the cable rather insignificant. This is the case for SSI serial link encoders.
NOTE: If a 24 V absolute SSI serial encoder is used, it is not necessary to connect the 5 V supply.
To ensure good working order in the case of interference, an encoder, whose metal casing is grounded by the connected device, must be chosen. The encoder must ground the connection cable shielding.
