December 2016, José Gaspar
In this page is published a
specification for encoding PLC hardware inputs to Petri net transitions.
An example of inputs mapping
is the following:
function inp_map= define_input_mapping
inp_map= { ...
0, 4 ; ... % input0 fires transition4
-(0+100), 5 ; ... % negated input0 fires t5
};
In this example one has the
input bit number 0 firing transitions numbers 4 and 5. In the first case the
input bit is used directly, while in the second case its negated logic value is
used instead. Notice that negating the input is represented by adding 100 to
the number of the bit, and prefixing the result with a minus sign.
The inputs specification
is used by the main compiling function plc_make_program.m
function plc_make_program(ofname, PN, input_map, output_map, show_places)
%
% Write to file a PLC program (structured text) given a Petri net (PN),
% and given the input/output physical mappings. May also add a list of
% places (only one active at each moment), to be shown as PLC outputs.
which calls
multiple times the auxiliary function plc_map_inputs.m :
function prg_tfire = plc_map_inputs( inp_bits_lst, trans_lst, options )
%
% inp_bits_lst : 1xN : PLC input module list of bits
% trans_lst : 1xN : Petri net transitions list (indexes, not strings)
%
% prg_tfire : list of strings : lines of structured text
This function is called
once per line of the Nx2 list inp_map previously introduced. The general description
of the inp_map is that the first column contains physical inputs specification while
the second column contains an identification of the Petri net transition. In
the following are various examples of specifications of input mappings.
First example, one input to
one transition:
inp_map= { 15, 25 }; % map input 15 (e.g. %i0.3.15) to transition
t25
Second example, AND of two
inputs to one transition:
inp_map= { [0 4]', 4 }; % input 0
AND input 4 -> transition
4
Third example, ANDs of pairs of inputs to transitions:
inp_map= { [1 2 3; 4 4
4], [5 6 3] };
%
i1 & i4 -> trans5
% i2 & i4 -> trans6
% i3 & i4 -> trans3
Fourth example, negating
entries of some inputs:
inp_map= { [-100 -101 -102 -103; 4 4 4 4],
[9 10 7 8] };
% NOT(i0)&i4 -> trans9
% NOT(i1)&i4 -> trans10
% NOT(i2)&i4 -> trans7
% NOT(i3)&i4 -> trans8
Fifth example, OR of ANDs and NOR of ANDs:
mylst= {{[0 1], [0 2], [0 3], [1 2], [1 3], [2
3]}};
inp_map= { struct('op', 'OR_of_ANDs', 'transId',28, 'lst',mylst), []};
inp_map= { struct('op', 'NOR_of_ANDs', 'transId',28, 'lst',mylst), []};
In this last case
transition 28 is the negation of a multi-entry OR. Each entry of the OR is a
Download the zip file pn_to_plc_v2.zip
and decompress it to a folder of your choice.
To run the main demo:
>>
cd tst1_blink_turn_on_off
>> tst1_blink_on_off
In case you find this
material useful and do any publication in the sequel please refer to the course
Industrial
Automation at Técnico,
|
Prof. José Gaspar Instituto de Sistemas e Robótica, Instituto Superior Técnico, Torre Norte Av. Rovisco Pais, 1 1049-001 |
Office:
Torre Norte do IST, 7.19 |