Omron NX-EC0112, Руководство пользователя

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7 SSI Input Units
NX-series Position Interface Units User’s Manual (W524)
7-6 I/O Refreshin
g Method
Setting
7
7-6
-6 Pro
cess Dat
a Co
mmunications
S
tatus
If it was not possible to read the initial value from the SSI encoder because the SSI encoder was not
connected, the power supply to the encoder is not turned ON, or for any other reason, an SSI commu-
nications error occurs in the SSI Input Unit.
When the SSI communications error is detected, the bit that corresponds to the SSI Input Unit in the
Process Data Communications Status is set along with the SSI Communications Error Status in the SSI
Status. In this case, the initial value of the encoder present position is not set and the initial state of the
Unit remains at 0.
However, you can start SSI communications with a command after the bit in the Process Data Commu-
nications Status is set. If SSI communications start normally, the SSI Communications Error Status is
reset and the read value is set as the encoder present position.
There is one bit for each Unit in the Process Data Communications Status.
For a Two-channel Unit, bit in the Process Data Communications Status is set when both channels are
ready to start SSI communications based on the results of the initial communications performed for
each channel.
The following figure shows an example of a Two-channel Unit where channel 1 completed initial com-
munications normally, but an error occurred for channel 2.
*1. An error occurred for CH2 when the initial value was read, so the present value is not updated.
*2. The bit in the Process Data Communications Status is set when both channels are ready to perform SSI com-
munications for a command.
When Initial Communications with the SSI Encoder Did Not Start
Normally
Two-channel Units
Unit initialization. Encoder initial value read. Ready for SSI communications command SSI Input Unit operation
Bit in Process Data
Communications Status that
corresponds to SSI Input Unit
SSI Communications Error
Status in SSI Status
Encoder present position 0
Power turned ON or Unit restarted.
SSI communications
error or other error
If the initial value was not read normally, the
encoder present position is not updated.
Unit initialization. Encoder initial value read. Ready for SSI communications command CH1 operation
CH1 Encoder Present Position 0 Initial value of the encoder present position
Unit initialization. Initial value is read. Ready for SSI communications command CH2 operation
Bit in Process Data
Communications Status that
corresponds to SSI Input Unit
CH2 SSI Communications
Error Status in CH2 SSI Status
CH2 Encoder Present Position 0
*1
Power turned ON or Unit restarted.
SSI communications error or other error
*2