SimStep Manual - 3400 Iss. D 7
th
June 2004 page 28
9.4 Write Ports
The
write ports
can be connected to an indicator (LED), an opto-isolator, a low-current
relay or another SimStep’s
read port
. The WP(bit pattern) command is used to write to
the output port
.
The bit pattern is specified as an eight digit binary number. The digits will be either
characters 0, 1 or 2 starting with
write port
8 through to 1. A 0 defines that the output will
be off, a 1 defines that the output will be on and a 2 defines that the output will not
change from its current state. The power-on states of the
write ports
are 00000000 - i.e. all
off.
The outputs are rated at 50mA, 35V.
9.4.1 Inductive Loads
The
write ports
must not be reverse biased. If used to drive an inductive load such as a
relay, then protection diodes must be used. If using an MSE891, this can be done by
connecting Diode-Com to 0V (either 0V on the Breakout box or the external supply 0V).
10
SimStep
Example Sequence
An example sequence is shown below. Three switches are connected to the
Read Port
to
control the action of the sequence and three outputs are used to monitor the action of the
sequence. One switch executes a 'home to datum' move and two switches initiate moves.
The ‘home to datum’ move must be done before the other moves can be selected.
The moves are controlled by the following inputs.
Read Port 1 = home to datum (datum search)
Read Port 2 = move to position 1
Read Port 3 = move to position 2
When the moves are completed, the following outputs turn on.
Write Port 1 = datum search complete
Write Port 2 = at position 1
Write Port 3 = at position 2
10.1 Sequence Definitions
Sequence 0 waits for the ‘Home to Datum’ input to be ‘1’ and then executes a ‘home to
datum’ (HD) move.
1ds0 Sequence 0 – Search for Datum
1wp22222000 Turn off outputs
1wa22222221 Wait for Home input to go on
1hd Search for datum
1we Wait for end of move
1wp22222001 Turn on axis 1 homed
1wa22222220 Wait for Home input to go off
1xs2 Goto input scanning sequence
1es
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