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doc/tipsandtricks.html
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doc/tipsandtricks.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<title>StreamDevice: Tips and Tricks</title>
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<link rel="shortcut icon" href="sls_icon.ico">
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<link rel="stylesheet" type="text/css" href="stream.css">
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<meta name="author" content="Dirk Zimoch">
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</head>
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<body>
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<h1>StreamDevice: Tips and Tricks</h1>
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<a name="argvar"></a>
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<h2>I have many almost identical protocols</h2>
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<p>
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You can give <a href="protocol.html#argvar">arguments</a> to a protocol.
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In the <code>INP</code> or <code>OUT</code> link, write:
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</p>
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<p>
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<code>
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field (OUT, "@protocolfile protocol(arg1,arg2,arg3) bus")
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</code>
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</p>
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<p>
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In the protocol, reference arguments as <code>$1 $2 $3</code> or inside strings
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as <code>"\$1 \$2 \$3"</code>.
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</p>
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<p>
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<code>
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moveaxis {out "move\$1 %.6f";}<br>
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field (OUT, "@motor.proto moveaxis(X) motor1")
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</code>
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</p>
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<p>
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<code>
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readpressure {out 0x02 0x00 $1; in 0x82 0x00 $1 "%2r";}<br>
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field (INP, "@vacuumgauge.proto readpressure(0x84) gauge3")
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</code>
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</p>
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<a name="iointr"></a>
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<h2>I have a device that sends unsolicited data</h2>
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<p>
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Use <a href="processing.html#iointr"><code>I/O Intr</code> processing</a>.
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The record receives any input and processes only when the input matches.
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</p>
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<p>
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<code>
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read {in "new value = %f";}
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</code>
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</p>
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<p>
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<code>
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record (ai, "$(RECORD)") {<br>
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field (DTYP, "stream")<br>
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field (INP, "@(DEVICETYPE).proto read $(BUS)")<br>
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field (SCAN, "I/O Intr")<br>
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}
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</code>
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</p>
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<a name="multiline"></a>
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<h2>I have a device that sends multi-line messages</h2>
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<pre>
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Here is the value:
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3.1415
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</pre>
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<p>
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Use as many <code>in</code> commands as you get input lines.
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</p>
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<p>
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<code>
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read_value {in "Here is the value:"; in "%f";}
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</code>
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</p>
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<a name="writemany"></a>
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<h2>I need to write more than one value in one message</h2>
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<p>
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There is more than one solution to this problem.
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Different approaches have different requirements.
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</p>
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<h3>A) All values have the same type and are separated by the same string</h3>
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<p>
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Use array records (e.g. <a href="waveform.html">waveform</a>,
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<a href="aao.html">aao</a>).
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</p>
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<p>
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<code>
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array_out {separator=", "; out "an array: (%.2f)";}
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</code>
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</p>
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<p>
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The format <code>%.2f</code> is repeated for each element of the array.
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All elements are separated by <code>", "</code>.<br>
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Output will look like this:
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<pre>
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an array: (3.14, 17.30, -12.34)
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</pre>
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</p>
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<h3>B) We have up to 12 numeric values</h3>
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<p>
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Use a <a href="calcout.html">calcout</a> record and
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<a href="formats.html#types">field references</a> in the format.
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</p>
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<p>
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<code>
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write_ABC {out "A=%(A).2f B=%(B).6f C=%(C).0f";}
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</code>
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</p>
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<p>
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You must specify a valid expression in the <code>CALC</code> field
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even if you don't use it.
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</p>
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<p>
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<code>
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record (calcout, "$(RECORD)") {<br>
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field (INPA, "$(A_RECORD)")<br>
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field (INPB, "$(B_RECORD)")<br>
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field (INPC, "$(C_RECORD)")<br>
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field (CALC, "0")<br>
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field (DTYP, "stream")<br>
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field (OUT, "@(DEVICETYPE).proto write_ABC $(BUS)")<br>
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}
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</code>
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</p>
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<h3>C) Values are in other records on the same IOC</h3>
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<p>
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Use <a href="formats.html#types">record references</a> in the format.
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</p>
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<p>
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<code>
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acquire {out 'ACQUIRE "%(\$1:directory.VAL)s/%s",%(\$1:time.VAL).3f;';}
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</code>
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</p>
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<p>
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You must specify the full <code>record.FIELD</code> name,
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even for <code>VAL</code> fields.
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To avoid record names in protocol files use
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<a href="protocol.html#argvar">protocol arguments</a>.
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In the link, specify the record name or just the basename of the
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other records (device name) in parentheses.
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</p>
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<p>
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<code>
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record (stringout, "$(DEVICE):getimage") {<br>
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field (DTYP, "stream")<br>
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field (OUT, "@(DEVICETYPE).proto acquire($(DEVICE)) $(BUS)")<br>
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}
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</code>
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</p>
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<a name="readmany"></a>
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<h2>I need to read more than one value from one message</h2>
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<p>
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Again, there is more than one solution to this problem.
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</p>
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<h3>A) All values have the same type and are separated by the same string</h3>
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<p>
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Use array records (e.g. <a href="waveform.html">waveform</a>,
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<a href="aai.html">aai</a>).<br>
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</p>
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<p>
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<code>
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array_in {separator=","; in "array = (%f)";}
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</code>
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</p>
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<p>
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The format <code>%f</code> is repeated for each element of the array.
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A <code>","</code> is expected beween element.<br>
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Input may look like this:
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</p>
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<pre>
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array = (3.14, 17.30, -12.34)
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</pre>
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<h3>B) The message and the values in it can be filtered easily</h3>
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<p>
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Use <a href="processing.html#iointr"><code>I/O Intr</code> processing</a>
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and <a href="formats.html#syntax">value skipping</a> (<code>%*</code>)<br>
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</p>
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<p>
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<code>
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read_A {out "GET A,B"; in "A=%f, B=%*f";}<br>
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read_B {in "A=%*f, B=%f";}
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</code>
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</p>
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<p>
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<code>
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record (ai, "$(DEVICE):A") {<br>
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field (DTYP, "stream")<br>
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field (INP, "@(DEVICETYPE).proto read_A $(BUS)")<br>
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field (SCAN, "1 second")<br>
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}<br>
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record (ai, "$(DEVICE):B") {<br>
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field (DTYP, "stream")<br>
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field (INP, "@(DEVICETYPE).proto read_B $(BUS)")<br>
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field (SCAN, "I/O Intr")<br>
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}
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</code>
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</p>
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<p>
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Record A actively requests values every second.
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The reply contains values A and B.
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Record A filters only value A from the input and ignores value B
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by using the <code>*</code> flag.
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Nevertheless, a complete syntax check is performed: B must be a
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valid floating point number.
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Record B is <code>I/O Intr</code> and gets (a copy of) any input, including
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input that was directed to record A.
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If it finds a matching string it ignores value A, reads value B and
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then processes.
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Any non-matching input is ignored by record B.
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</p>
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<h3>C) Values should be stored in other records on the same IOC</h3>
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<p>
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Use <a href="formats.html#types">record references</a> in the format.
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To avoid record names in protocol files, use
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<a href="protocol.html#argvar">protocol arguments</a>.
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</p>
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<p>
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<code>
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read_AB {out "GET A,B"; in "A=%f, B=%(\$1.VAL)f";}
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</code>
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</p>
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<p>
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<code>
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record (ai, "$(DEVICE):A") {<br>
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field (DTYP, "stream")<br>
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field (INP, "@(DEVICETYPE).proto read_AB($(DEVICE):B) $(BUS)")<br>
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field (SCAN, "1 second")<br>
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}<br>
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record (ai, "$(DEVICE):B") {<br>
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}
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</code>
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</p>
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<p>
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Whenever record A reads input, it stores the first value in its own VAL field
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as usual and the second in the VAL field of record B.
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Because the VAL field of record B has the PP attribute, this automatically
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processes record B.
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</p>
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<a name="mixed"></a>
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<h2>I have a device that sends mixed data types: numbers and strings</h2>
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<p>
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Use a <code>@mismatch</code>
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<a href="protocol.html#except">exception handler</a> and
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<a href="formats.html#types">record references</a> in the format.
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To avoid record names in protocol files, use
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<a href="protocol.html#argvar">protocol arguments</a>.
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</p>
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<h3>Example</h3>
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<p>
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When asked "<code>CURRENT?</code>", the device send something like
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"<code>CURRENT 3.24 A</code>" or a message like
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"<code>device switched off</code>".
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</p>
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<p>
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<code>
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read_current {out "CURRENT?"; in "CURRENT %f A"; @mismatch {in "%(\1.VAL)39c";}}
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</code>
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</p>
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<p>
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<code>
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record (ai, "$(DEVICE):readcurrent") {<br>
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field (DTYP, "stream")<br>
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field (INP, "@(DEVICETYPE).proto read_current($(DEVICE):message) $(BUS)")<br>
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}<br>
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record (stringin, "$(DEVICE):message") {<br>
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}
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</code>
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</p>
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<p>
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After <a href="processing.html#proc">processing</a> the readcurrent record, you can see from
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SEVR/STAT if the read was successful or not.
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With some more records, you can clean the message record if SEVR is not INVALID.
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</p>
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<code>
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record (calcout, "$(DEVICE):clean_1") {<br>
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field (INPA, "$(DEVICE):readcurrent.SEVR CP")<br>
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field (CALC, "A!=2")<br>
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field (OOPT, "When Non-zero")<br>
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field (OUT, "$(DEVICE):clean_2.PROC")<br>
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}<br>
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record (stringout, "$(DEVICE):clean_2") {<br>
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field (VAL, "OK")<br>
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field (OUT, "$(DEVICE):message PP")<br>
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}<br>
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</code>
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<hr>
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<p><small>Dirk Zimoch, 2007</small></p>
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<script src="stream.js" type="text/javascript"></script>
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</body>
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</html>
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