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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>S7plc EPICS driver</title>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<meta name="author" content="Dirk Zimoch">
<style type="text/css">
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</style>
</head>
<body>
<h1>S7plc EPICS driver documentation</h1>
<h2>Contents</h2>
<ol>
<li><a href="#intro">Introduction</a></li>
<li><a href="#theory">Theory of Operation</a></li>
<li><a href="#config">Driver Configuration</a></li>
<li><a href="#device">Device Support</a>
<ol>
<li><a href="#stat">Connection Status</a></li>
<li><a href="#ai">Analog Input</a></li>
<li><a href="#ao">Analog Output</a></li>
<li><a href="#bi">Binary Input</a></li>
<li><a href="#bo">Binary Output</a></li>
<li><a href="#mbbi">Multibit Binary Input</a></li>
<li><a href="#mbbo">Multibit Binary Output</a></li>
<li><a href="#mbbiDirect">Multibit Binary Input Direct</a></li>
<li><a href="#mbboDirect">Multibit Binary Output Direct</a></li>
<li><a href="#longin">Long Input</a></li>
<li><a href="#longout">Long Output</a></li>
<li><a href="#stringin">String Input</a></li>
<li><a href="#stringout">String Output</a></li>
<li><a href="#waveform">Waveform Input</a></li>
<li><a href="#calcout">Calculation Output</a></li>
</ol></li>
<li><a href="#driver">Driver Functions</a></li>
</ol>
<a name="intro"></a>
<h2>1 Introduction</h2>
<p>
This driver is intended to connect a Siemens S7 PLC (programmable
logic controller) via TCP/IP to an EPICS IOC, using the so called
"send/receive" protocol.
However, it can be used for any device sending and receiving blocks of
process variables (PVs) in the same way.
I highly recommend to connect to the PLC on a separate physical
network using a second network interface to avoid connection problems.
</p>
<p>
The driver was originally developped for SLS (Swiss Light Source) in 2000.
Later is has been modified by DESY (Deutsches Elektronen Synchrotron). The
current version has been completely rewritten for PPT (Puls-Plasmatechnik GmbH)
to run on a R3.14.6 PC based system, but it can also run on R3.13 vxWorks
system. Author of the current version is
<a href="mailto:Dirk Zimoch <dirk.zimoch@psi.ch>">Dirk
Zimoch <dirk.zimoch@psi.ch></a>.
</p>
<p>
In this document, it is assumed that the reader is familiar with EPICS, the
record concept and meanings of the fields of the standard records.
Recommended documentation: EPICS Record Refecrence Manual.
</p>
<a name="theory"></a>
<h2>2 Theory of Operation</h2>
<p>
The driver and the PLC periodically exchange data (process variables)
over the network.
For each direction (IOC to PLC and PLC to IOC), there is one fixed size
data block that bundles all process variables for this direction.
The process variables are identified by their bytes offset in the data
block.
</p>
<p>
Process variables can be 8, 16, or 32 bit wide signed or unsigned integers
or bit fields, single or double precision floating point values,
or arrays of these, as well as strings of single byte characters.
Both byte orders, big endian and little endian, are supported.
</p>
<p>
The IOC programmer typically connects one input record to each process
variable sent from the PLC to the IOC and one output record for each
process variable sent from the IOC to the PLC.
This requires that the programmer of the PLC and the programmer of the IOC
agree on the data block sizes and layouts.
The layout is not negotiated between IOC and PLC in any automated way.
</p>
<p>
When the IOC starts, the driver tries to connect to the PLC
which must run a TCP server.
If connection cannot be established (e.g. because the PLC is off)
the driver periodically retries to set up the connection.
Once connected, the driver waits for data blocks sent by the PLC.
The PLC must be set up to send its data periodically.
If the driver does not receive any data within a configurable timeout
(which should be 2 to 10 times the send period of the PLC) or the
data block does not have the correct size, the driver considers the
communication broken and closes the connection.
After a short time it tries to reconnect.
<p>
Upon reciving the data block, the driver copies the process variables
from this block into input records and then triggers processing of the
records.
To allow this triggering, the input records should use "I/O Intr" scanning
(or alternatively be processed by another record that uses "I/O Intr"
and is conencted to the same PLC).
All input records connected to the same PLC are triggered at the same time
after all input values have been updated.
The order of processing is undefined.
</p>
<p>
On the other hand, the driver periodically checks if any of the output
records connected to this PLC has processed since the last cycle.
If and only if this is the case, a data block containing all output
variables is sent to the PLC.
Sending output only starts after the "PINI" run at IOC startup.
This allows to initialize all output records before any data is sent
to the IOC.
Thus all output records should have the "PINI" field set to "YES" (or
alternatively be processed by another record that uses "PINI").
Any output that has not been processed before the data block is sent
to the PLC transfers only 0 bytes (usually meaning integer 0, floating
point 0.0, or empty string, depending on the data type).
<p>
Data blocks are always transfered completely.
That means all process variables in that block are transfered, even
if they have not changed since the last cycle.
There is no way to write or read only a sub-set of process variables.
In between two cycles, any number of process variables may have changed.
These changes are only transfered to the other communication partner
in the next cycle.
Thus, there is always a delay until the values update on the other side
of the connection.
Also if values change too quickly, faster than the transfer cycle,
intermediate values are lost.
</p>
<a name="config"></a>
<h2>3 Driver Configuration</h2>
<p>
In the IOC startup script, the s7plc driver needs to be configured:
</p>
<p class="indent">
<code>
s7plcConfigure (<i>PLCname</i>, <i>IPaddr</i>, <i>port</i>, <i>inSize</i>,
<i>outSize</i>, <i>bigEndian</i>, <i>recvTimeout</i>, <i>sendIntervall</i>)
</code>
</p>
<p>
<code><i>PLCname</i></code> is an arbitrary symbolic name for the PLC running
a server TCP socket on <code><i>IPaddr</i>:<i>port</i></code>.
The records reference the PLC with this name in their <code>INP</code> or
<code>OUT</code> link. <code><i>PLCname</i></code> must not contain the
slash character (<code>/</code>).
</p>
<p>
<code><i>inSize</i></code> and <code><i>outSize</i></code> are the data block
sizes in bytes read from and sent to the PLC, respectively. Any of them can
be <code>0</code>. Byte order is defined by <code><i>bigEndian</i></code>. If
this is <code>1</code>, the IOC expects the PLC to send and receive any
multibyte PV (word, float, etc) most significant byte first. If it is
<code>0</code>, the data is least significant byte first. This is independent
of the byte order of the IOC.
</p>
<p>
If the IOC does not receive new data from the PLC for
<code><i>recvTimeout</i></code> milliseconds, it closes the connection and
tries to reopen it after a few seconds. <code><i>recvTimeout</i></code>
should be 2 to 10 times the send intervall of the PLC.
</p>
<p>
The IOC checks for data to send every <code><i>sendIntervall</i></code>
milliseconds. If any output record has been processed in this time, the
complete buffer is sent to the PLC. If no new output is available, nothing
is sent.
</p>
<h4>Example:</h4>
<p class="indent">
<code>
s7plcConfigure ("vak-4", "192.168.0.10", 2000, 1024, 32, 1, 500, 100)
</code>
</p>
<p>
In the vxWorks target shell, <code><i>PLCname</i></code>, and
<code><i>IPaddr</i></code> must be quoted. In the iocsh, quotes are
optional.
</p>
<p>
The variable <code>s7plcDebug</code> can be set in the statup script or
at any time on the command line to change the amount or debug output.
The following levels are supported:
</p>
<p>
-1: fatal errors only<br>
0: errors only<br>
1: startup messages<br>
2:+ output record processing<br>
3:+ inputput record processing<br>
4:+ driver calls<br>
5:+ io printout<br>
</p>
<p>
Be careful using level>1 since many messages can introduce considerable
delays which may result in connection losses. Default level is 0.
</p>
<p>
On vxWorks, <code>s7plcDebug</code> can be set with
<code>s7plcDebug=<i>level</i></code>
</p>
<p>
In the iocsh use
<code>var s7plcDebug <i>level</i></code>
</p>
<a name="device"></a>
<h2>4 Device Support</h2>
<p>
The driver supports the standard record types <a href="#ai">ai</a>,
<a href="#ao">ao</a>, <a href="#bi">bi</a>, <a href="#bo">bo</a>,
<a href="#mbbi">mbbi</a>, <a href="#mbbo">mbbo</a>,
<a href="#mbbiDirect">mbbiDirect</a>, <a href="#mbboDirect">mbboDirect</a>,
<a href="#longin">longin</a>, <a href="#longout">longout</a>,
<a href="#stringin">stringin</a>, <a href="#stringout">stringout</a>,
and <a href="#waveform">waveform</a>. With EPICS R3.14,
<a href="#calcout">calcout</a> is supported, too.
The <code>DTYP</code> is <code>"S7plc"</code>. If the record processes when
the PLC is not connected (off, down, unreachable), the record raises an
alarm with <code>SEVR="INVALID"</code> and <code>STAT="CONN"</code>.
</p>
<p>
There is also a connection status support for <a href="#stat">bi</a>. The
<code>DTYP</code> is <code>"S7plc stat"</code>. This record does not
raise an alarm when the PLC is disconnected. It just changes to
<code>0</code> state in that case.
</p>
<p>
<code>SCAN="I/O Intr"</code> is supported. Whenever input data is received
from a PLC, all <code>"I/O Intr"</code> input records connected to this PLC
are processed. In each output cyle, all <code>"I/O Intr"</code> output
records are processed.
</p>
<p>
The general form of the <code>INP</code> or <code>OUT</code> link is
</p >
<p class="indent">
<code>
"@<i>PLCname</i>/<i>offset</i> T=<i>type</i> L=<i>low</i> H=<i>high</i> B=<i>bit</i>"
</code>
</p>
<p>
Not all parameters <code>T</code>, <code>L</code>, <code>H</code>, and
<code>B</code> are required for each record type and parameters equal to the
default value may be omitted. The default values depend on the record type.
</p>
<p>
<code><i>PLCname</i></code> is the PLC name as defined by
<code>s7plcConfigure</code> in the startup script.
</p>
<p>
<code><i>offset</i></code> is the byte offset of the PV relative to the
beginning of the input or output data block for this PLC. It must be an
integer number or a sum of integer numbers like <code>20+3+2</code>.
</p>
<p>
<code>T=<i>type</i></code> defines the data type for transmitting the PV
from or to the PLC. It is not case sensitive and has several aliases (see
table <a href="#type">below</a>).
The default is <code>T=INT16</code> for most record types.
<code>L=<i>low</i></code> and <code>H=<i>high</i></code> are used in analog
input and output records if <code>LINR</code> is set to <code>"LINEAR"</code>
to convert analog values to integer values and back. They define the raw
values which correspond to <code>EGUL</code> and <code>EGUF</code>,
respectively.
Analog output records will never write integer values lower than
<code>L</code> or higher than <code>H</code>. If necessary, the raw output
value is truncated to the nearest limit. The default values for
<code>L</code> and <code>H</code> depend on <code>T</code>.
</p>
<a name="type"></a>
<center>
<table border=1 cellpadding=5>
<tr>
<th>T=</th><th>Data Type</th><th>Default L=</th><th>Default H=</th>
</tr>
<tr>
<td><tt>INT8</tt>
</td><td>8 bit (1 byte) signed integer number</td>
<td><tt>-0x7F<br>-127</tt></td>
<td><tt>0x7F<br>127</tt></td>
</tr>
<tr>
<td><tt>UINT8<br>UNSIGN8<br>BYTE<br>CHAR</tt>
</td><td>8 bit (1 byte) unsigned integer number</td>
<td><tt>0x00<br>0</tt></td>
<td><tt>0xFF<br>255</tt></td>
</tr>
<tr>
<td><tt>INT16<br>SHORT</tt></td>
<td>16 bit (2 bytes) signed integer number</td>
<td><tt>-0x7FFF<br>-32767</tt></td>
<td><tt>0x7FFF<br>32767</tt></td>
</tr>
<tr>
<td><tt>UINT16<br>UNSIGN16<br>WORD</tt></td>
<td>16 bit (2 bytes) unsigned integer number</td>
<td><tt>0x0000<br>0</tt></td>
<td><tt>0xFFFF<br>65535</tt></td>
</tr>
<tr>
<td><tt>INT32<br>LONG</tt></td>
<td>32 bit (4 bytes) signed integer number</td>
<td><tt>-0x7FFFFFFF<br>-2147483647</tt></td>
<td><tt>0x7FFFFFFF<br>2147483647</tt></td>
</tr>
<tr>
<td><tt>UINT32<br>UNSIGN32<br>DWORD</tt></td>
<td>32 bit (4 bytes) unsigned integer number</td>
<td><tt>0x00000000<br>0</tt></td>
<td><tt>0xFFFFFFFF<br>4294967295</tt></td>
</tr>
<tr>
<td><tt>REAL32<br>FLOAT32<br>FLOAT</tt></td>
<td>32 bit (4 bytes) floating point number</td>
<td>N/A</td><td>N/A</td>
</tr>
<tr>
<td><tt>REAL64<br>FLOAT64<br>DOUBLE</tt></td>
<td>64 bit (8 bytes) floating point number</td>
<td>N/A</td><td>N/A</td>
</tr>
<tr>
<td><tt>STRING</tt></td>
<td>character array</td>
<td>40</td><td>N/A</td>
</tr>
</table>
</center>
<p>
If <code>T=STRING</code>, <code>L</code> means <i>length</i>, not <i>low</i>.
The default value is the length of the <code>VAL</code> field.
In the case of the stringin and stringout records, this is 40 (including
the terminating null byte).
</p>
<p>
<code>B=<i>bit</i></code> is only used for bi and bo records to define the
bit number within the data byte, word, or doubleword (depending on
<code>T</code>). Bit number 0 is the least significant bit.
Note that in big endian byte order (also known as motorola format) bit 0 is
in the last byte, while in little endian byte order (intel format) bit 0 is
in the first byte. If in doubt, use <code>T=BYTE</code> to avoid all
byte order problems when handling single bits.
</p>
<p>
Note that the output buffer is initialised with null bytes at startup and
any output record that has not been processed after reboot will send null
values to the PLC. The driver does not send anything before the global
variable <code>interruptAccept</code> has been set <code>TRUE</code> at the
end of <code>iocInit</code>. All records with <code>PINI</code> set to
<code>"YES"</code> have already been processed by that time. The driver
does not change the <code>VAL</code> field of any output record at
initialisation. Thus, auto save and restore can be used in combination with
<code>PINI="YES"</code>.
</p>
<a name="stat"></a>
<h3>4.1 Connection Status</h3>
<pre>
record (bi, "$(RECORDNAME)") {
field (DTYP, "S7plc stat")
field (INP, "@$(PLCNAME)")
field (SCAN, "I/O Intr")
}
</pre>
<p>
The record value is 1 if a connection to the PLC is established and 0 if not.
Disconnect does not raise an alarm.
</p>
<a name="ai"></a>
<h3>4.2 Analog Input</h3>
With conversion from integer data type:
<pre>
record (ai, "$(RECORDNAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET) T=$(T) L=$(L) H=$(H)")
field (SCAN, "I/O Intr")
field (LINR, "Linear")
field (EGUL, "$(MINVAL)")
field (EGUF, "$(MAXVAL)")
}
</pre>
Using floating point data type:
<pre>
record (ai, "$(RECORDNAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (SCAN, "I/O Intr")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
Defaults for <code>L</code> and <code>H</code> depend
on <code>T</code> (see table <a href="#type">above</a>).
</p>
<p>
If <code>T</code> is an integer type, the PV is read into
<code>RVAL</code>. If <code>LINR</code> is set to <code>"LINEAR"</code>,
then the record support converts <code>RVAL</code> to <code>VAL</code>
so that <code>RVAL=L</code> converts to <code>VAL=EGUL</code> and
<code>RVAL=H</code> converts to <code>VAL=EGUF</code>.
</p>
<p>
<code>VAL<sub>temp</sub>=(RVAL-L)*(EGUF-EGUL)/(H-L)+EGUL</code>
</p>
<p>
After this conversion, <code>VAL<sub>temp</sub></code> is still
subject to scaling and smoothing.
</p>
<p>
<code>VAL=(VAL<sub>temp</sub>*ASLO+AOFF)*(1-SMOO)+VAL<sub>old</sub>*SMOO</code>.
</p>
<p>
If <code>T=FLOAT</code> or <code>T=DOUBLE</code>,
the PV is read directly into <code>VAL</code> and <code>L</code>,
<code>H</code>, <code>EGUL</code> and <code>EGUF</code> are ignored.
The device support emulates scaling and smoothing which is otherwise done
by the record support during conversion.
</p>
<p>
<code>VAL=(<i>PV</i>*ASLO+AOFF)*(1-SMOO)+VAL<sub>old</sub>*SMOO</code>
</p>
<p>
<code>T=STRING</code> is not valid for ai records.
</p>
<a name="ao"></a>
<h3>4.3 Analog Output</h3>
With conversion to integer data type:
<pre>
record (ao, "$(RECORDNAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) T=$(T) L=$(L) H=$(H)")
field (LINR, "Linear")
field (PINI, "YES")
field (EGUL, "$(MINVAL)")
field (EGUF, "$(MAXVAL)")
}
</pre>
Using floating point data type:
<pre>
record (ao, "$(RECORDNAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (PINI, "YES")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
Defaults for <code>L</code> and <code>H</code> depend
on <code>T</code> (see table <a href="#type">above</a>).
</p>
<p>
If <code>T</code> is an integer type, <code>RVAL</code> is
written to the PV. If <code>LINR</code> is set to <code>"LINEAR"</code>,
then the record support first scales <code>OVAL</code>.
</p>
<p>
<code>OVAL<sub>temp</sub>=(OVAL-AOFF)/ASLO</code>
</p>
<p>
After that, the value is converted to <code>RVAL</code> so that
<code>OVAL<sub>temp</sub>=EGUL</code> converts to <code>RVAL=L</code> and
<code>OVAL<sub>temp</sub>=EGUF</code> converts to <code>RVAL=H</code>.
</p>
<p>
<code>RVAL=(OVAL<sub>temp</sub>-EGUL)*(H-L)/(EGUF-EGUL)+L</code>
</p>
<p>
If <code>RVAL</code> is higher than <code>H</code> or lower than
<code>L</code>, the value is truncated to the nearest limit.
</p>
<p>
If <code>T=FLOAT</code> or <code>T=DOUBLE</code>,
<code>OVAL</code> is written directly to the PV. <code>L</code>,
<code>H</code>, <code>EGUL</code> and <code>EGUF</code> are ignored.
The device support emulates scaling which is otherwise done by the
record support during conversion.
</p>
<p>
<code><i>PV</i>=(OVAL-AOFF)/ASLO</code>
</p>
<p>
<code>T=STRING</code> is not valid for ao records.
</p>
<a name="bi"></a>
<h3>4.4 Binary Input</h3>
<pre>
record(bi, "$(NAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET) T=$(T) B=$(B)")
field (SCAN, "I/O Intr")
}
</pre>
<p>
Default type is <code>T=INT16</code>. Default bit is <code>B=0</code>.
</p>
<p>
Depending on <code>T</code>, <code>B</code> can vary from 0 to 7, 15, or 31.
Bit 0 is the least significant bit. In little endian byte order, bit 0 is in
the first byte, in big endian byte order it is in the last byte of the PV.
If in doubt, use <code>T=BYTE</code> to avoid all byte order problems when
handling single bits.
</p>
<p>
The PV is read to <code>RVAL</code> and masked with
2<sup><code>B</code></sup>.
<code>VAL</code> is 1 if <code>RVAL</code> is not 0.
</p>
<p>
<code>RVAL=<i>PV</i>&(1<<B); VAL=(RVAL!=0)?1:0</code>
</p>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for bo records. Signed and unsigned types are equivalent.
</p>
<a name="bo"></a>
<h3>4.5 Binary Output</h3>
<pre>
record(bo, "$(NAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) T=$(T) B=<i>bit</i>")
field (PINI, "YES")
}
</pre>
<p>
Default type is <code>T=INT16</code>. Default bit is <code>B=0</code>.
</p>
<p>
Depending on <code>T</code>, <code>B</code> can vary from 0 to 7, 15, or 31.
Bit 0 is the least significant bit. In little endian byte order, bit 0 is in
the first byte, in big endian byte order it is in the last byte of the PV.
If in doubt, use <code>T=BYTE</code> to avoid all byte order problems when
handling single bits.
</p>
<p>
If <code>VAL</code> is not 0, then <code>RVAL</code> is set to
2<sup><code>B</code></sup>, else <code>RVAL</code> is set to 0.
Only the referenced bit of the PV is changed while all other bits remain
untouched. Thus, other output records can write to different bits of the
same PV.
<p>
<code>RVAL=(VAL!=0)?(1<<<i>bit</i>):0;
<i>PV</i>=(<i>PV</i><sub>old</sub>&~(1<<<i>bit</i>))|RVAL</code>
</p>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for bo records. Signed and unsigned types are equivalent.
</p>
<a name="mbbi"></a>
<h3>4.6 Multibit Binary Input</h3>
<pre>
record(mbbi, "$(NAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (SCAN, "I/O Intr")
field (NOBT, "$(NUMBER_OF_BITS)")
field (SHFT, "$(RIGHT_SHIFT)")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
</p>
<p>
The PV is read to <code>RVAL</code>, shifted right by <code>SHFT</code> bits
and masked with <code>NOBT</code> bits. Valid values for <code>NOBT</code>
and <code>SHFT</code> depend on <code>T</code>:
<code>NOBT</code>+<code>SHFT</code> must not exceed the number of bits of
the type.
</p>
<p>
Bit 0 is the least significant bit. In little endian byte order, bit 0 is in
the first byte, in big endian byte order it is in the last byte of the PV.
</p>
<p>
<b>Example:</b> Use bits 4 to 9 out of 16.
<code>T=INT16</code>, <code>NOBT=6</code>, <code>SHFT=4</code>
</p>
<table border=1 cellspacing=0>
<tr>
<td>PV</td>
<th bgcolor="#c0c0c0" width="5%">15</th>
<th bgcolor="#c0c0c0" width="5%">14</th>
<th bgcolor="#c0c0c0" width="5%">13</th>
<th bgcolor="#c0c0c0" width="5%">12</th>
<th bgcolor="#c0c0c0" width="5%">11</th>
<th bgcolor="#c0c0c0" width="5%">10</th>
<th width="5%">9</th>
<th width="5%">8</th>
<th width="5%">7</th>
<th width="5%">6</th>
<th width="5%">5</th>
<th width="5%">4</th>
<th bgcolor="#c0c0c0" width="5%">3</th>
<th bgcolor="#c0c0c0" width="5%">2</th>
<th bgcolor="#c0c0c0" width="5%">1</th>
<th bgcolor="#c0c0c0" width="5%">0</th>
</tr>
<tr>
<td>RVAL</td>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th>9</th>
<th>8</th>
<th>7</th>
<th>6</th>
<th>5</th>
<th>4</th>
</tr>
</table>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for mbbi records. Signed and unsigned types are equivalent.
</p>
<a name="mbbo"></a>
<h3>4.7 Multibit Binary Output</h3>
<pre>
record(mbbo, "$(NAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (PINI, "YES")
field (NOBT, "$(NUMBER_OF_BITS)")
field (SHFT, "$(LEFT_SHIFT)")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
</p>
<p>
RVAL is masked with <code>NOBT</code> bits, shifted left by
<code>SHFT</code> bits and written to the PV. Valid values for
<code>NOBT</code> and <code>SHFT</code> depend on <code>T</code>:
<code>NOBT</code>+<code>SHFT</code> must not exceed the number of bits of
the type.
</p>
<p>
Bit 0 is the least significant bit. In little endian byte order, bit 0 is in
the first byte, in big endian byte order it is in the last byte of the PV.
</p>
<p>
Only the referenced <code>NOBT</code> bits of the PV are changed. All other
bits remain untouched. Thus, other output records can write to different bits
of the same PV.
</p>
<p>
<b>Example:</b> Use bits 5 to 8 out of 16.
<code>T=INT16</code>, <code>NOBT=4</code>, <code>SHFT=5</code>
</p>
<table border=1 cellspacing=0>
<tr>
<td>RVAL</td>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th bgcolor="#c0c0c0"> </th>
<th>8</th>
<th>7</th>
<th>6</th>
<th>5</th>
</tr>
<tr>
<td>PV</td>
<th bgcolor="#c0c0c0" width="5%">15</th>
<th bgcolor="#c0c0c0" width="5%">14</th>
<th bgcolor="#c0c0c0" width="5%">13</th>
<th bgcolor="#c0c0c0" width="5%">12</th>
<th bgcolor="#c0c0c0" width="5%">11</th>
<th bgcolor="#c0c0c0" width="5%">10</th>
<th bgcolor="#c0c0c0" width="5%">9</th>
<th width="5%">8</th>
<th width="5%">7</th>
<th width="5%">6</th>
<th width="5%">5</th>
<th bgcolor="#c0c0c0" width="5%">4</th>
<th bgcolor="#c0c0c0" width="5%">3</th>
<th bgcolor="#c0c0c0" width="5%">2</th>
<th bgcolor="#c0c0c0" width="5%">1</th>
<th bgcolor="#c0c0c0" width="5%">0</th>
</tr>
</table>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for mbbo records. Signed and unsigned types are equivalent.
</p>
<a name="mbbiDirect"></a>
<h3>4.8 Multibit Binary Input Direct</h3>
<pre>
record(mbbiDirect, "$(NAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (SCAN, "I/O Intr")
field (NOBT, "$(NUMBER_OF_BITS)")
field (SHFT, "$(RIGHT_SHIFT)")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
</p>
<p>
The PV is read to <code>VAL</code>, shifted right by <code>SHFT</code>
bits and masked with <code>NOBT</code> bits (see <a href="#mbbi">mbbi</a>).
Valid values for <code>NOBT</code> and <code>SHFT</code> depend
on <code>T</code>: <code>NOBT</code>+<code>SHFT</code> must
not exceed the number of bits of the type.
</p>
<p>
Bit 0 is the least significant bit. In little endian byte order, bit 0 is in
the first byte, in big endian byte order it is in the last byte of the PV.
</p>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for mbbiDirect records. Signed and unsigned types are equivalent.
</p>
<a name="mbboDirect"></a>
<h3>4.9 Multibit Binary Output Direct</h3>
<pre>
record(mbboDirect, "$(NAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (PINI, "YES")
field (NOBT, "$(NUMBER_OF_BITS)")
field (SHFT, "$(LEFT_SHIFT)")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
</p>
<p>
VAL is masked with <code>NOBT</code> bits, shifted left by <code>SHFT</code>
bits and written to the PV (see <a href="#mbbo">mbbo</a>). Valid values for
<code>NOBT</code> and <code>SHFT</code> depend on <code>T</code>:
<code>NOBT</code>+<code>SHFT</code> must not exceed the number of bits of
the type.
</p>
<p>
Bit 0 is the least significant bit. In little endian byte order, bit 0 is in
the first byte, in big endian byte order it is in the last byte of the PV.
</p>
<p>
Only the referenced <code>NOBT</code> bits of the PV are changed. All other
bits remain untouched. Thus, other output records can write to different bits
of the same PV.
</p>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for mbboDirect records. Signed and unsigned types are equivalent.
</p>
<a name="longin"></a>
<h3>4.10 Long Input</h3>
<pre>
record(longin, "$(NAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (SCAN, "I/O Intr")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
</p>
<p>
The PV is read to <code>VAL</code>. If the type has less than 32 bits, the
value is zero extended or sign extended depending on the signedness of
the type.
</p>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for longin records.
</p>
<a name="longout"></a>
<h3>4.11 Long Output</h3>
<pre>
record(longout, "$(NAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) T=$(T)")
field (PINI, "YES")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
</p>
<p>
Depending on <code>T</code>, the least significant 8, 16, or 32 bytes
of <code>VAL</code> are written to the PV.
</p>
<p>
<code>T=STRING</code>, <code>T=FLOAT</code> or <code>T=DOUBLE</code> are not
valid for longout records.
</p>
<a name="stringin"></a>
<h3>4.12 String Input</h3>
<pre>
record(stringin, "$(NAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET) L=$(LENGTH)")
field (SCAN, "I/O Intr")
}
</pre>
<p>
Default and only valid type is <code>T=STRING</code>.
Default length is <code>L=40</code>.
</p>
<p>
<code>L</code> bytes are read from the PV to <code>VAL</code> and null
terminated. Thus, the effective string length is maximal
<code>L</code>-1 bytes.
</p>
<a name="stringout"></a>
<h3>4.13 String Output</h3>
<pre>
record(stringout, "$(NAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) L=$(LENGTH)")
field (PINI, "YES")
}
</pre>
<p>
Default and only valid type is <code>T=STRING</code>.
Default length is <code>L=40</code>.
</p>
<p>
<code>L</code> bytes are written from <code>VAL</code> to the PV.
If the actual string length of <code>VAL</code> is shorter than
<code>L</code>, the remaining space is filled with null bytes. If
it is longer than <code>L</code>, the string is truncated and not
null terminated
</p>
<a name="waveform"></a>
<h3>4.14 Waveform Input</h3>
<pre>
record(waveform, "$(NAME)") {
field (DTYP, "S7plc")
field (INP, "@$(PLCNAME)/$(OFFSET)")
field (SCAN, "I/O Intr")
field (NELM, "$(NUMBER_OF_ELEMENTS)")
field (FTVL, "$(DATATYPE)")
}
</pre>
<p>
<code>NELM</code> elements are read from the PV to <code>VAL</code>.
</p>
<p>
The default type depends on <code>FTVL</code>. For example
<code>FTVL=LONG</code> results in <code>T=INT32</code>.
<code>T</code> and <code>FTVL</code> must match but can differ
in signedness. In most cases, better just specify <code>FTVL</code> and
leave <code>T</code> to the default.
</p>
<p>
If <code>T=STRING</code>, <code>FTVL</code> must be <code>"CHAR"</code> or
<code>"UCHAR"</code>. <code>L=<i>length</i></code> can be specified but
defaults to and must not exceed <code>NELM</code>.
If <code>L</code> is less than <code>NELM</code>, the
remaining elements are left untouched.
</p>
<p>
<code>FTVL="STRING"</code> is not supported.
</p>
<p>
The special type <code>T=TIME</code> is supported for
waveforms records only. <code>FTVL</code> must be
<code>"CHAR"</code> or <code>"UCHAR"</code> and <code>NELM</code> should be
<code>"8"</code>. The input bytes are converted from BCD (binary coded decimal)
to integer values in the range from 0 to 99 each. This type is intended
to transfer BCD coded real time clock timestamps.
</p>
<p>
The Siemens "STEP 7" manual defines the 8 byte PLC timetamp as follows:
</p>
<table border=1 cellspacing=0>
<tr>
<th>0</th>
<th>1</th>
<th>2</th>
<th>3</th>
<th>4</th>
<th>5</th>
<th>6</th>
<th>7</th>
</tr>
<tr>
<td>year</td>
<td>month</td>
<td>day</td>
<td>hour</td>
<td>minute</td>
<td>second</td>
<td>msec(hi)</td>
<td>msec(lo)*10+day of week</td>
</tr>
</table>
<p>
Years 90 to 99 mean 1990 to 1999, years 0 to 89 mean 2000 to 2089. Months
and days start with 1. Hour is 0 to 23, minute and second 0 to 59. Msec are
milliseconds in the range 0 to 999. The first two digits (0-99 hundredth of
a second) are in msec(hi). The last digit (0-9 thousandth of a second)
is multiplyed by 10 and added to the day of week (Sunday=1 to Saturday=7).
If you want to have the unconverted BCD bytes, do not use
<code>T=TIME</code>.
</p>
<a name="calcout"></a>
<h3>4.15 Calculation Output</h3>
<pre>
record(calcout, "$(NAME)") {
field (DTYP, "S7plc")
field (OUT, "@$(PLCNAME)/$(OFFSET) T=$(T) L=$(L) H=$(H)")
field (PINI, "YES")
}
</pre>
<p>
Default type is <code>T=INT16</code>.
Defaults for <code>L</code> and <code>H</code> depend
on <code>T</code> (see table <a href="#type">above</a>).
</p>
<p>
<code>OVAL</code> (the result of <code>CALC</code> or <code>OCAL</code>,
depending on <code>DOPT</code>) is written to the PV. If
<code>T</code> is an integer type, the value is truncated to an
integer and compared to <code>L</code> and <code>H</code>.
If <code>OVAL</code> is lower than <code>L</code> or higher than
<code>H</code>, it is truncated to the nearest limit.
</p>
<p>
If <code>T=FLOAT</code> or <code>T=DOUBLE</code>,
<code>OVAL</code> is written to the PV directly without any conversion.
</p>
<p>
<code>T=STRING</code> is not valid for calcout records.
</p>
<p>
To use this device support with calcout records, you need EPICS R3.14.
</p>
<a name="driver"></a>
<h2>5 Driver Functions</h2>
<p>
Device support for other record types can be written with calls to the
following driver functions:
</p>
<p>
<code>
s7plcStation* s7plcOpen (char* PLCname);
</code>
</p>
<p class="indent">
<code>
int s7plcRead (s7plcStation* station,
unsigned int offset, unsigned int dlen,
void* pdata);
</code>
</p>
<p class="indent">
<code>
int s7plcReadArray (s7plcStation* station,
unsigned int offset, unsigned int dlen,