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--- becki:linux:modbus [2010-07-22 15:46]
becki created
+++ becki:linux:modbus [2013-06-13 13:56] (aktuell)
becki
@@ Zeile 1: / Zeile 1: @@
 ====== Modbus TCP ==
-Collected informations for using [[wp>Modbus]] on TCP/IP. Libmodbus is used as master on any Linux computer ([[Sheevaplug]]). Wago fieldbuscouplers [[http://www.wagocatalog.com/okv3/index.asp?strBestNrID=7500342|750-342]] are used as slaves.
+Collected informations for using [[wp>Modbus]] on TCP/IP. Libmodbus is used as master on any Linux computer ([[Sheevaplug]]). Wago fieldbuscouplers [[http://www.wago.com/wagoweb/documentation/750/ger_manu/342/m034200d.pdf|750-342]] (or alternatively [[http://www.wago.com/wagoweb/documentation/750/ger_manu/841/m084100d.pdf|750-841]]) are used as slaves.
+===== Modbus Command Overview ==
+^ Code ^ Target ^ Count ^ Direction ^  Name in Spec             ^ Libmodbus 3 fkt name                ^  libmodbus 2 fkt name         ^
+|  ''01 0x01'' |  DO   |  many  |  read     | Read Coils                | ''modbus_read_bits''                | ''read_coil_status''          |
+|  ''02 0x02'' |  DI   |  many  |  read     | Read Discrete Inputs      | ''modbus_read_input_bits''          | ''read_input_status''         |
+|  ''03 0x03'' |  AO   |  many  |  read     | Read Holding Registers    | ''modbus_read_registers''           | ''read_holding_registers''    |
+|  ''04 0x04'' |  AI   |  many  |  read     | Read Input Register       | ''modbus_read_input_registers''     | ''read_input_registers''      |
+|  ''05 0x05'' |  DO   |  one   |  write    | Write Single Coil         | ''modbus_write_bit''                | ''force_single_coil''         |
+|  ''06 0x06'' |  AO   |  one   |  write    | Write Single Register     | ''modbus_write_register''           | ''preset_single_register''    |
+|  ''15 0x0f'' |  DO   |  many  |  write    | Write Multiple Coils      | ''modbus_write_bits''               | ''force_multiple_coils''      |
+|  ''16 0x10'' |  AO   |  many  |  write    | Write Multiple registers  | ''modbus_write_registers''          | ''preset_multiple_registers'' |
+|  ''23 0x17'' | AI/AO |  many  |  both     | Wrt/Rd Multiple registers | ''modbus_write_and_read_registers'' |  :?:  |
+Sources [[http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b.pdf|Spec]] [[http://libmodbus.org/site_media/html/libmodbus.html|Manpage]]
+More information sources:
+  * http://www.anybus.de/technologie/modbustcp.shtml
+  * http://www.modbus.org/docs/PI_MBUS_300.pdf
+  * http://jamod.sourceforge.net/kb/protocol.html
 ===== Wago 750-342 ==
@@ Zeile 27: / Zeile 47: @@
 ipNumber= bootpEnabled ? getIpNumberFromBootpServer() : getIpNumberFromEeprom()
 </code>
+Web access to 750-342 is ''admin / wago''
 See also: [[http://www.wago.com/wagoweb/documentation/750/ger_manu/841/m084100d.pdf|Wago manual]] p.82ff and [[man>bootptab]]
 ===== Libmodbus ==
+==== Usage / Doc  ==
+See http://libmodbus.org/site_media/html/libmodbus.html
 ==== Installation ==
+Download the [[http://github.com/downloads/stephane/libmodbus/libmodbus-3.0.2.tar.gz|source]] and use the [[http://think-deep.com/becki/slackbuilds/pack.php?n=libmodbus|Slack build script]].
+<note warning>The rest of this section is obsolete</note>
 Note: You could get the latest devel release with ''git clone http://github.com/stephane/libmodbus.git'', but this has no ''configure'' script, so we use the lataest stable release instead.
-Download v 2.0.3 from [[http://copyleft.free.fr/wordpress/index.php/libmodbus/|here]] and do the usual ''./confiure; make; su; make install;''. This installs the following objects to ''/usr/local/'':
+Download v 2.0.3 from [[http://libmodbus.org/download/|here]]
+Libmodbus has the unpleasant behaviour, that it prints error messages to ''stdout'' instead of ''stderr''. If you plan to build your application like a filter which commuicates over ''stdin / stdout'' to the world, than you will get problems, in that libmodbus may interfere your protocoll or whatever with error messages. Therfore we patch the source a little bit and are writing error messages to ''stderr'' instead of ''stdout''. Look for the function ''error_treat'' in ''modbus/modbus.c'' and replace the ''printf'' function with ''fprintf'':
+<code c>
+static void error_treat(modbus_param_t *mb_param, int code, const char *string)
+{
+        printf("\nERROR %s (%d)\n", string, code);
+</code>
+<code c>
+static void error_treat(modbus_param_t *mb_param, int code, const char *string)
+{
+        fprintf(stderr, "\nERROR %s (%d)\n", string, code);
+</code>
+Now do the usual ''./confiure; make; su; make install;''. This installs the following objects to ''/usr/local/'':
   lib/libmodbus.so
@@ Zeile 44: / Zeile 90: @@
   include/modbus/modbus.h
 Then do ''ldconfig'' to update the library system info.
+===== Wago Adressing in Libmodbus ==
+==== Bit-based access to digital IOs ==
+  * Bit-based function codes are # 1,2,5,15
+  * The first digital input and output bits have both address 0
+  * The 2nd digital input and output bits have both address 1
+  * Addressing of inputs and outputs are independent (ie. there exists DI 0 and DO 0)
+  * Each input/output bit consumes one member of the ''uint8_t dest[]'' array. I.e. each bit consumes one byte.
+==== Register-based access to analog IOs ==
+  * Register-based (16bit) function codes are # 3,4,6,16
+  * The first analog input and output register have both address 0
+  * Contrary to the Wago manuals the 2nd analog input and output registers have address 1 :!:
+==== Register-based access to digital IOs ==
+  * Access to digital inputs and outputs is also possible with the register-based function codes
+  * Digital input and output addresses are automatically appended after the analog addresses. This means the digital addresses are dependend of the number of the analog devices.
+  * Each digital IO consumes on //bit// in the ''uint16_t dest[]'' array

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