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74 lines
2.6 KiB
Markdown
74 lines
2.6 KiB
Markdown
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## How to Get Simulation Time from the Variable Server
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For historical reasons ```sys.exec.out.time``` is the name given to simulation time in data recording files. ```sys.exec.out.time``` isn’t a real variable in a Trick sim. So you can’t get it from the variable server directly.
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The way to get the sim time from the Trick variable server is to get the following two variables and then calculate the sim-time.
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```trick_sys.sched.time_tic_value``` - **integer** that represents the number of tics per second.
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```trick_sys.sched.time_tics``` - **integer** that represents the current simulation time in time tics.
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To calculate the simulation time:
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1. Convert the value of ```trick_sys.sched.time_tics``` to a floating point number.
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2. Then divide that by the value of ```trick_sys.sched.time_tic_value```.
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Below is a simple Python variable server client that gets and prints simulation time for any modern Trick based simulation.
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To invoke it:
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```
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$ ./SimTimeExample.py <variable-server-port-number>
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```
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### Example (SimTimeExample.py)
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```python
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#!/usr/bin/python
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import sys
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import socket
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# Process the command line arguments.
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if ( len(sys.argv) == 2) :
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trick_varserver_port = int(sys.argv[1])
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else :
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print( "Usage: vsclient <port_number>")
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sys.exit()
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# Connect to the variable server.
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client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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client_socket.connect( ("localhost", trick_varserver_port) )
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insock = client_socket.makefile("r")
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client_socket.send( "trick.var_pause()\n" )
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client_socket.send( "trick.var_ascii()\n" )
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# Get the number of tics per second (just once).
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client_socket.send( "trick.var_add(\"trick_sys.sched.time_tic_value\")\n")
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client_socket.send( "trick.var_send()\n" )
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line = insock.readline()
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field = line.split("\t")
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tics_per_second = int(field[1]);
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client_socket.send( "trick.var_clear()\n" )
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# Get the number of time_tics, and whatever else you want to recieve periodically.
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client_socket.send( "trick.var_add(\"trick_sys.sched.time_tics\") \n"
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)
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# Start the flow of data from the variable server.
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client_socket.send( "trick.var_unpause()\n" )
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# Repeatedly read and process the responses from the variable server.
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while(True):
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line = insock.readline()
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if line == '':
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break
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field = line.split("\t")
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time_tics = int(field[1]);
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# Calculate sim_time
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sim_time = float(time_tics) / tics_per_second
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print 'sim_time = {0}'.format(sim_time)
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```
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If you are unfamiliar or rusty on how to use the Trick variable server, please see
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the [Variable Server](TutVariableServer) section of the [Trick Tutorial](Tutorial).
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