b2d7721d20
* Updated example code from Python 2 to 3 in How to Get Simulation Time from the Variable Server How-To Guide. * Removed one line of commented code. * Modified the examples in Trick Variable Server Tutorial from Python2 to 3 mainly due to socket send in bytes plus print statement update need for Python 3. * Fixed 2 missed print statements.
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How to Get Simulation Time from the Variable Server
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.
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.
trick_sys.sched.time_tic_value - integer that represents the number of tics per second.
trick_sys.sched.time_tics - integer that represents the current simulation time in time tics.
To calculate the simulation time:
- Convert the value of
trick_sys.sched.time_ticsto a floating point number. - Then divide that by the value of
trick_sys.sched.time_tic_value.
Below is a simple Python variable server client that gets and prints simulation time for any modern Trick based simulation.
To invoke it:
$ ./SimTimeExample.py <variable-server-port-number>
Example (SimTimeExample.py)
#!/usr/bin/python3
import sys
import socket
# Process the command line arguments.
if ( len(sys.argv) == 2) :
trick_varserver_port = int(sys.argv[1])
else :
print( "Usage: vsclient <port_number>")
sys.exit()
# Connect to the variable server.
client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect( ("localhost", trick_varserver_port) )
insock = client_socket.makefile("r")
client_socket.send( b"trick.var_pause()\n" )
client_socket.send( b"trick.var_ascii()\n" )
# Get the number of tics per second (just once).
client_socket.send( b"trick.var_add(\"trick_sys.sched.time_tic_value\")\n" )
client_socket.send( b"trick.var_send()\n" )
line = insock.readline()
field = line.split("\t")
tics_per_second = int(field[1]);
client_socket.send( b"trick.var_clear()\n" )
# Get the number of time_tics, and whatever else you want to recieve periodically.
client_socket.send( b"trick.var_add(\"trick_sys.sched.time_tics\") \n" )
# Start the flow of data from the variable server.
client_socket.send( b"trick.var_unpause()\n" )
# Repeatedly read and process the responses from the variable server.
while(True):
line = insock.readline()
if line == '':
break
field = line.split("\t")
time_tics = int(field[1]);
# Calculate sim_time
sim_time = float(time_tics) / tics_per_second
print(f'sim_time = {sim_time}')
If you are unfamiliar or rusty on how to use the Trick variable server, please see the Variable Server section of the Trick Tutorial.