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Topic Details for Soft Logic

Help - Soft Logic Configuration

Overview:

The soft logic system has its own data table which is independent of the main system (or communications) data table). The soft logic IO configuration provides the connection between the two data tables. Without a soft logic IO configuration, the soft logic program will run, but it will have no way to connect to real world IO or to the HMI.

Configuration:

Configuration is performed through a configuration file called "mblogic.config". This file holds all the data table names, addresses, and other required information. This is a plain text file which can be edited with any text editor. The configuration file is defined as follows:

One line per parameter. Each parameter must appear on a separate line.
Comments. Any line beginning with a "hash" ("#") character is a comment and is ignored.
Sections. Sections begin a series of related configuration values. A section name is an identifier which is enclosed by square brackets ("[ ]"). A section includes all items until the beginning of a new section, or until the end of the file.
Configuration items. Any line following the beginning of a section is considered to be an item which belongs to that section (excluding comments). Configuration items are key/value pairs in the format "key=value".

System Identification:

The configuration must include a section named "&system". The system identification section is used to define parameters which apply to the overall soft logic system. These factors are:

type - This defines which soft logic library will be used to interpret the soft logic program. Only the "ck" library exists at present. Others may be added in future.
plcprog - This determines the name used for the softlogic program file. Set this to the name you wish to use for your program file.
scan - This is the target scan rate in milli-seconds. The system will attempt to run your soft logic program once every 'x' milli-seconds, where 'x' is the value you provide. See the comments on application considerations below with regards to how to set this value.

Example:


	[&system]
	type=ck
	plcprog=plcprog.txt
	scan=50

Data Table Save/Restore:

The configuration must include a section named "&logicsave". This section is used to define parameters which apply to the data table save and restore system (see the help topic on "Soft Logic Data Table Save" for details on how this works). These factors are:

updateinterval - This defines the minimum update interval. This must be a valid integer or floating point number.
wordaddr - This is a list of soft logic word addresses which are to be saved to disk. These may be any valid word (not boolean) addresses. Individual addresses must be separated by commas.

Example:


	[&logicsave]
	updateinterval=2.0
	wordaddr=DS1,DS2,DS3,DS4,DS5,DS6,DS7,DS8,DS9,DS10

IO Sections:

The remainder of the configuration consists of "IO sections". An IO section defines a group of addresses which are two be transferred between the two data tables. The section names are arbitrary, and the user is free to select any name desired provided it does not start with an ampersand ("&"). Names starting with an ampersand (e.g. "&system") are considered special and reserved for use by the soft logic system.

Address Types:

Address types determine how data is stored in the system data table. This includes the number of storage locations (e.g. registers) and the byte ordering. For numeric address types which occupy multiple registers, the least significant word is stored in the platform's native format. For Intel type CPUs (big endian), the first (lower address) register. For string data types, characters are stored in consecutively increasing addresses. The following address types are currently defined:

Address Type	Data Type	Storage Location	# Storage Elements	Soft Logic Address Compatibility	Extended Data Type
coil	boolean	coil	1	X, Y, C	No
discrete	boolean	discrete inputs	1	X, Y, C	No
holdingreg	signed 16 bit integer	holding register	1	'DS', 'XD', 'YD', 'XS', 'YS'	No
inputreg	signed 16 bit integer	input register	1	'DS', 'XD', 'YD', 'XS', 'YS'	No
holdingreg32	signed 32 bit integer	holding register	2	DD	Yes
inputreg32	signed 32 bit integer	input register	2	DD	Yes
holdingregfloat	single precision (32 bit) floating point	holding register	2	DF	Yes
inputregfloat	single precision (32 bit) floating point	input register	2	DF	Yes
holdingregdouble	double precision (64 bit) floating point	holding register	4	DF	Yes
inputregdouble	double precision (64 bit) floating point	input register	4	DF	Yes
holdingregstr8	string	holding register	2 characters per register	TXT	Yes
inputregstr8	string	input register	2 characters per register	TXT	Yes
holdingregstr16	string	holding register	1 character per register	TXT	Yes
inputregstr16	string	input register	1 character per register	TXT	Yes

Configuring IO Sections:

An IO section must contain the following items:

addrtype - This defines the type of system data table address. It must be one of the address types listed above.
base - This is the beginning of the block of system data table addresses defined. The number of addresses used will depend on the number of soft logic addresses defined in the "logictable" parameter.
action - This must be either "read" or "write". Specifying "read" will cause the IO section to transfer data from the system data table to the soft logic table. Specifying "write" will cause the IO section to transfer data to the system data table from the soft logic table.
logictable - This must be one or more valid soft logic addresses, with multiple addresses separated by commas (e.g. "X1,Y10,C9". This defines the soft logic data table addresses that data will be transferred to or from. Addresses do not need to be in any particular order, but the must all be of a compatible type. Native data types may define multiple addresses. Extended data types are limited to a single address.
strlen - This parameter is only used with string length. It defines the maximum number of characters for the string. This parameter is ignored for other data types.

Example:


	[PBs]
	addrtype=coil
	base=32100
	action=read
	logictable=X1,X2,X3,X4,X5,X6,X7,X8


	[PartCount]
	addrtype=holdingreg32
	base=42
	action=write
	logictable=DS101


	[PartName]
	addrtype=inputregstr16
	base=1234
	action=read
	logictable=TXT99
	strlen=10

Review the documentation on the system data table before deciding which registers, coils, or discrete inputs to use.

Application Considerations:

Grouping IO Addresses:

A configuration must include one (and only one) "system identification" ("&system") section. It may include as many "IO" sections as desired. The IO sections may be given meaningful names (e.g. "PushButtons"). However, the primary purpose of a section is to group associated addresses together so they can be dealt with efficiently. A good approach is to have each IO section represent an field device module or IO card(s). This of course assumes that the client and server commands for the system data table have been grouped in this manner.

Addresses in the system data table are handled most efficiently when they are read or written in consecutive blocks.

For the soft logic data table, it does not matter what order addresses are in, or whether they are grouped together. This means that if you wish to group or organise addresses in your program differently in your soft logic program than they are organised in the actual field devices, it is best to do this in the soft logic configuration and to leave the actual IO communications in their natural order.

Soft Logic Program Name:

The name used for the soft logic program is defined in the system parameters (see above). Any name can be used, provided it doesn't conflict with the name of a file which is part of the system (e.g. one of the configuration files). The file can also have any file extension desired or even no file extension. This allows names such as "Machine_021.prog" or "Water_System.txt" (or whatever else is desired).

Program Scan Rate:

The soft logic program target scan rate is defined in the system parameters (see above). The target scan rate means that the system will attempt to run one scan of the soft logic program at the requested interval. Note that this is the desired scan rate, not the measured rate.

A soft logic system differs from a conventional PLC in that the soft logic system is running on a general purpose computer platform. There may be other things such as HMIs, databases, and other tasks running on the same platform. On a conventional PLC, to add more features you would normally just add more hardware modules (with each feature needing its own hardware to run on). A soft logic system will often have to share the hardware with other applications. This means that the soft logic system cannot assume that all the computing resources are available for its exclusive use.

For a soft logic system, this means that taking up 100% of the CPU capacity to scan the program as fast as possible is not a good idea. In a new application, the target scan rate should be initially set to a larger value (e.g. 50 msec) and then adjusted downwards to smaller values as needed. The amount of CPU capacity being used can be measured by using the normal operating system utilities for whatever operating system you are using (e.g. "top" or "System Monitor" for Linux, or the equivalent utility for MS Windows).

The program scan rate is set at system start up and cannot be changed while the system is running. This means that to change the scan rate, you need to stop and restart the system.

Changing the Configuration:

The soft logic IO configuration is specified in a configuration file. This file is read when the system starts up. However, the configuration can also be changed while the system is running by reloading the configuration using the system "status" interface. Details of how to do this may be found in the help pages which are part of the status system.

Complete Example:

The following shows a complete example.


	# Test configuration for soft logic system.
	# 17-Jun-2009
	
	# System parameters.
	# Set the type of soft logic, the default PLC program name, 
	# and the target scan rate.
	[&system]
	type=ck
	plcprog=plcprog.txt
	scan=50
	
	# Data table values to save to disk, along with
	# the minimum update interval.
	[&logicsave]
	updateinterval=2.0
	wordaddr=DD1,DF2,DS10
	
	############################################
	
	# Each section must be given a unique name. The name can be descriptive, but
	# must not start with an ampresand ('&').
	
	# Get the push buttons.
	[PBs]
	addrtype=coil
	base=32100
	action=read
	logictable=X1,X2,X3,X4,X5,X6,X7,X8
	
	# Set the pilot lights.
	[PLs]
	addrtype=discrete
	base=32100
	action=write
	logictable=Y1,Y2,Y3,Y4,Y5,Y6,Y7,Y8
	
	# Get PB4 register.
	[PB4]
	addrtype=holdingreg
	base=32200
	action=read
	logictable=XD1
	
	# Set PL4 register.
	[PL4]
	addrtype=inputreg
	base=32200
	action=write
	logictable=YD1
	
	# Tank Readings. These are Tank1 level, Tank2 levell, and Pump Speed (actual).
	[Tanks]
	addrtype=inputreg
	base=32210
	action=write
	logictable=YS10,YS11,YS12
	
	# Pump command speed.
	[PumpCommand]
	addrtype=holdingreg
	base=32210
	action=read
	logictable=XS10
	
	#########################################################
	
	# Strip charts.
	[StripCharts]
	addrtype=inputreg
	base=32213
	action=write
	logictable=YS20,YS21
	
	
	############################################
	
	# Events.
	[Events]
	addrtype=coil
	base=32300
	action=write
	logictable=Y20,Y21,Y22,Y23,Y24,Y25,Y26,Y27,Y28
	
	# Alarms.
	[Alarms]
	addrtype=coil
	base=32400
	action=write
	logictable=Y30,Y31,Y32,Y33,Y34,Y35,Y36,Y37,Y38
	
	############################################
	
	# Test the extended data types.
	
	# 32 bit integer.
	[HRInt32Read]
	addrtype=holdingreg32
	base=32215
	action=read
	logictable=DD10
	
	[IRInt32Read]
	addrtype=inputreg32
	base=32215
	action=read
	logictable=DD11
	
	# Single precision floating point.
	[HRFloat32Read]
	addrtype=holdingregfloat
	base=32217
	action=read
	logictable=DF10
	
	[IRFloat32Read]
	addrtype=inputregfloat
	base=32217
	action=read
	logictable=DF11
	
	
	# Double precision floating point.
	[HRFloat64Read]
	addrtype=holdingregdouble
	base=32219
	action=read
	logictable=DF13
	
	[IRFloat64Read]
	addrtype=inputregdouble
	base=32219
	action=read
	logictable=DF14
	
	# Strings
	[HRStrin8Read]
	addrtype=holdingregstr8
	base=32223
	action=read
	logictable=TXT10
	strlen=10
	
	[HRStrin8Write]
	addrtype=inputregstr8
	base=32223
	action=write
	logictable=TXT50
	strlen=10
	
	
	[Testholdingregstr16]
	addrtype=holdingregstr16
	base=32233
	action=read
	logictable=TXT100
	strlen=14
	
	[Testinputregstr16]
	addrtype=inputregstr16
	base=32233
	action=write
	logictable=TXT150
	strlen=14
	
	
	[Testholdingregstr16]
	addrtype=holdingregstr16
	base=32233
	action=read
	logictable=TXT100
	strlen=14
	
	[Testinputregstr16]
	addrtype=inputregstr16
	base=32233
	action=write
	logictable=TXT150
	strlen=14
	
	############################################