additional docs or training for socket comms in 42
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Hi, I'd like to know if there are any other resources (other than Docs in the repo here), for example videos or tutorials that can be shared for 42.
It'd be especially helpful if there is any content on running the Tx/Rx features for setting up a real-time simulator with real hardware inputs.
For example I want to know how to send messages to the ICP server that update the orientation and rotation rates of the spacecraft.
do I just put the client in READFILE mode and have my custom hardware "server" write to that file in realtime?
Hi Doug,
To answer your first question, I'm not aware of any other training resources out there.
You have, I'm sure, run the TxRx and Standalone example problems, right? Once you've done that, if you still don't see your way forward, come back and I'll try to get you pointed in the right direction.
Regards,
-Eric (he/him)
Yes, the Tx and Rx examples run for me okay. I have the networking all good, one device is Tx (display hidden) and another device is Rx.
I want to specifically send just the orientation vector (say from custom hardware or spoofed from software) to the simulator as Tx though, not run a full simulation as Tx.
So Rx would run a normal simulation, but Tx would feed just a few parameters (orientation and maybe angular velocity) at a possibly irregular or on-command interval, and Rx would update the simulator when it sees new data.
Would I write the vector to file from Tx in a specific format and then have Rx read the file in another socket?
Hi Doug,
Good, then you're almost there. I wouldn't suggest using READFILE, RX will work better for you. Let 42 be the Rx end of the socket. Your external app needs to take the place of the Tx end of the socket. (Which end is the server and which is the client is up to you; 42 can do either.) Your app needs to send messages over the socket that look like this:
TIME 2014-172-00:00:04.500000000
SC[0].B[0].wn = -1.748865083681e-03 -6.927475621347e-03 2.421122225958e-03
SC[0].B[0].qn = 4.985869992252e-01 2.909902747759e-01 6.853904088098e-02 8.136572153337e-01
[EOF]
wn are your angular rates, qn is your attitude.
In Inp_IPC.txt, set "Allow Blocking" to FALSE, so 42 won't wait for messages from your app. It will carry on as a normal sim, overwriting wn and qn when they come in from your app.
I think that should do it. Let me know if it doesn't.
Regards,
-Eric (he/him)
Thanks Eric, this helps a lot.
Do you have any recommendation for how to send messages over the socket via port 10001 (like a simple software to send packets)...
I'm familiar with UART for physical connections and SCP for network, but not so much network expertise to send arbitrary bytes on any port (e.g. 10001)..
Hi Doug,
42 uses TCP, which (if I understand right) guarantees that packets get delivered intact and in order (the other option would be UDP, which is fire-and-forget). The messages you send are in plain text (inefficient I know, but easy to check). If you're coding in C, you can crib from 42/Kit/Source/iokit.c to initialize your socket, and study 42/Source/IPC/AppWriteToSocket.c to see how one amateur builds and sends a message.
I know that Matlab, Julia, and the Godot game engine all have socket functionality. I assume it's pretty common. But I'm a dynamicist, not a network guru, so you're on your own to figure that part out. ;-)
Good luck,
-Eric (he/him)
Hi, when I run 42 with all my previous settings the same with this Inp_IPC.txt, the simulation windows don't appear...
<<<<<<<<<<<<<<< 42: InterProcess Comm Configuration File >>>>>>>>>>>>>>>>
1 ! Number of Sockets
********************************** IPC 0 *****************************
RX ! IPC Mode (OFF,TX,RX,TXRX,ACS,WRITEFILE,READFILE)
0 ! AC.ID for ACS mode
"State00.42" ! File name for WRITE or READ
SERVER ! Socket Role (SERVER,CLIENT,GMSEC_CLIENT)
localhost 10001 ! Server Host Name, Port
FALSE ! Allow Blocking (i.e. wait on RX)
TRUE ! Echo to stdout
3 ! Number of TX prefixes
"SC" ! Prefix 0
"Orb" ! Prefix 1
"World" ! Prefix 2
I get this output in the terminal:
dfranz@flatsat2:~/dev/42$ ./42 Horis
#0.0 Point SC[5].B[0] Primary Vector [0.0 0.0 -1.0] at SC[4]
#0.0 Align SC[5].B[0] Secondary Vector [0.0 1.0 0.0] with L-frame Vector [0.0 1.0 0.0]
#0.0 Align SC[6].B[0] Primary Vector [0.0 0.0 1.0] with L-frame Vector [1.0 0.0 1.0]
#0.0 Point SC[6].B[0] Secondary Vector [1.0 0.0 0.0] at SUN
#0.0 Point SC[0].B[0] Primary Vector [0.0 0.0 0.0] at SUN
Reached CmdScript EOF at Time = 0.000000
Server is listening on port 10001
and then it just hangs... Shouldn't it run the sim and show the GUIs since Allow Blocking is FALSE ?
I guess maybe my external application has to send a message on the socket for it to start up.
EDIT: Looks like I figured it out.
Leaving this comment for posterity if folks want a python example for making packets.
It was indeed just waiting for a message to start up. Is there a special message I should send the first time? When I send a telemetry message as a byte-string like your example the sim boots up and GUI displays and then it instantly crashes. I'm guessing it's somehow formatted wrong.
This is my code for generating a packet to send via TCP:
import socket
import datetime
from numpy import round
# Define the target IP and port
target_ip = "192.168.105.118"
target_port = 10001
# Create a TCP socket
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
# Connect to the server
sock.connect((target_ip, target_port))
# Define the bytes to send
#data_to_send = b"TIME 2014-172-00:00:04.500000000\nSC[0].B[0].wn = -1.748865083681e-03 -6.927475621347e-03 2.421122225958e-03\nSC[0].B[0].qn = 4.985869992252e-01 2.909902747759e-01 6.853904088098e-02 8.136572153337e-01\n[EOF]"
#data_to_send = "TIME 2014-172-00:00:04.500000000\n"
now = datetime.datetime.utcnow() + datetime.timedelta(seconds=15) # send it for 15 seconds ahead of current time.
data_to_send = "TIME " + str(now.year) + "-" + str(now.timetuple().tm_yday).zfill(3) + "-" + \
str(now.hour).zfill(2) + ":" + str(now.minute).zfill(2) + ":" + str(now.second).zfill(2) + "." + str(round(now.microsecond / 1e6, 1))[2:] + "0"*8
data_to_send += "\n"
data_to_send += "SC[0].B[0].wn = -1.748865083681e-03 -6.927475621347e-03 2.421122225958e-03"
data_to_send += "\n"
data_to_send += "SC[0].B[0].qn = 4.985869992252e-01 2.909902747759e-01 6.853904088098e-02 8.136572153337e-01"
data_to_send += "\n"
data_to_send += "[EOF]"
print("sending this packet: \n")
print(data_to_send)
print()
print()
data_to_send = data_to_send.encode()
# Send data
sock.sendall(data_to_send)
# Optional: receive response (if any)
# does work but we don't want to RX for now...
#response = sock.recv(1024)
#print("Received:", response)
The output looks like this and I've confirmed it can send (and receive!) on 10001.
dfranz@flatsat2:~/dev/42$ python comms.py
sending this packet:
TIME 2024-318-18:38:34.500000000
SC[0].B[0].wn = -1.748865083681e-03 -6.927475621347e-03 2.421122225958e-03
SC[0].B[0].qn = 4.985869992252e-01 2.909902747759e-01 6.853904088098e-02 8.136572153337e-01
[EOF]
When I run 42 on the server side, I get this
dfranz@flatsat2:~/dev/42$ python start_horis.py
starting HORIS simulation at 2024-11-13T18:38:05.544053
#0.0 Point SC[5].B[0] Primary Vector [0.0 0.0 -1.0] at SC[4]
#0.0 Align SC[5].B[0] Secondary Vector [0.0 1.0 0.0] with L-frame Vector [0.0 1.0 0.0]
#0.0 Align SC[6].B[0] Primary Vector [0.0 0.0 1.0] with L-frame Vector [1.0 0.0 1.0]
#0.0 Point SC[6].B[0] Secondary Vector [1.0 0.0 0.0] at SUN
#0.0 Point SC[0].B[0] Primary Vector [0.0 0.0 0.0] at SUN
Reached CmdScript EOF at Time = 0.000000
Server is listening on port 10001
Server side of socket established.
Initializing GLUT
Initializing Cam Window
Loading Cam Shaders
Loading Cam Textures
Loading 3D Noise
Loading Cam Lists
Cam Window Width = 800
Cam Window Height = 800
Cam Screen Width = 1920
Cam Screen Height = 1080
Done Initializing Cam Window
Attempted divide by zero in UNITV (Line 337 of mathkit.c)
Attempted divide by zero in UNITV (Line 337 of mathkit.c)
42 Case ./Horis/ is 0% Complete at Time = 0.000
TIME 2024-318-18:38:05.600000000
SC[0].PosR = 5.660000022928e-04 2.829999994247e-04 2.499999984755e+00
SC[0].VelR = 5.660000068866e-03 2.829999982742e-03 -3.049094579090e-07
SC[0].svb = -6.171589644297e-01 -7.219102022866e-01 -3.129863774329e-01
SC[0].bvb = 7.732720898955e-07 -4.279303478159e-06 2.477303116126e-05
SC[0].Hvb = 7.613642680502e-06 2.400848642731e-05 1.868473844966e-05
SC[0].AC.ParmLoadEnabled = 0
SC[0].AC.ParmDumpEnabled = 0
SC[0].AC.MAG[0].Field = 1.020000000000e-06
SC[0].AC.MAG[1].Field = -4.150000000000e-06
SC[0].AC.MAG[2].Field = 2.440000000000e-05
SC[0].AC.ST[0].Valid = 0
SC[0].AC.ST[0].qn = 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00
SC[0].AC.GPS[0].Valid = 1
SC[0].AC.GPS[0].Rollover = 2
SC[0].AC.GPS[0].Week = 292
SC[0].AC.GPS[0].Sec = 3.262665000000e+05
SC[0].AC.GPS[0].PosN = -6.888146723253e+06 -6.712743555995e-01 2.324921628097e+00
SC[0].AC.GPS[0].VelN = 1.208364759997e-01 9.864567641804e+02 -7.542928827482e+03
SC[0].AC.GPS[0].PosW = -6.113854455650e+06 -3.172864925975e+06 -1.664745377885e+04
SC[0].AC.GPS[0].VelW = -6.695990804712e+02 1.330107604536e+03 -7.542869364481e+03
SC[0].AC.GPS[0].Lng = -2.662889899260e+00
SC[0].AC.GPS[0].Lat = -2.416828597614e-03
SC[0].AC.GPS[0].Alt = 5.100017232535e+05
SC[0].AC.GPS[0].WgsLng = -2.662889899260e+00
SC[0].AC.GPS[0].WgsLat = -2.431903218556e-03
SC[0].AC.GPS[0].WgsAlt = 5.100098487309e+05
SC[0].B[0].wn = 1.745021122957e-03 5.236116186155e-03 3.490619050893e-03
SC[0].B[0].qn = 8.725875756771e-05 2.618025935650e-04 1.745319365380e-04 9.999999466920e-01
SC[0].GN.Pos = 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00
SC[0].GN.PosRate = 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00
SC[0].GN.Ang = 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00
SC[0].GN.AngRate = 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00
Orb[0].PosN = -6.888144957995e+06 9.863410943317e+01 -7.542863398130e+02
Orb[0].VelN = 8.401046591749e-01 9.863405783117e+02 -7.542859451961e+03
World[1].PosH = 4.760323816177e+10 -3.733144126492e+10 -7.421638605738e+09
World[1].eph.PosN = 4.760323816177e+10 -3.733144126492e+10 -7.421638605738e+09
World[1].eph.VelN = 2.043433973185e+04 4.054159888913e+04 1.408554858921e+03
World[2].PosH = 9.819320449585e+10 -4.662437908632e+10 -6.300195061170e+09
World[2].eph.PosN = 9.819320449585e+10 -4.662437908632e+10 -6.300195061170e+09
World[2].eph.VelN = 1.482154501853e+04 3.148686584600e+04 -4.331495447394e+02
World[3].PosH = 9.135421387102e+10 1.164620400449e+11 0.000000000000e+00
World[3].eph.PosN = 9.135421387102e+10 1.164620400449e+11 0.000000000000e+00
World[3].eph.VelN = -2.392250305550e+04 1.827049774703e+04 0.000000000000e+00
World[4].PosH = 1.618624104987e+10 2.326237528193e+11 4.454727349971e+09
World[4].eph.PosN = 1.618624104987e+10 2.326237528193e+11 4.454727349971e+09
World[4].eph.VelN = -2.326736954623e+04 3.746132192680e+03 6.516257419389e+02
World[5].PosH = 2.070163391273e+11 7.288781428189e+11 -7.703390348279e+09
World[5].eph.PosN = 2.070163391273e+11 7.288781428189e+11 -7.703390348279e+09
World[5].eph.VelN = -1.273433487085e+04 4.187507730886e+03 2.666572277461e+02
World[6].PosH = 1.414478581829e+12 -2.973112368589e+11 -5.096627629985e+10
World[6].eph.PosN = 1.414478581829e+12 -2.973112368589e+11 -5.096627629985e+10
World[6].eph.VelN = 1.442227980340e+03 9.410027546319e+03 -2.228414907840e+02
World[7].PosH = 1.632312439429e+12 2.434404302250e+12 -1.221217690382e+10
World[7].eph.PosN = 1.632312439429e+12 2.434404302250e+12 -1.221217690382e+10
World[7].eph.VelN = -5.684866692481e+03 3.474532615639e+03 8.663882962692e+01
World[8].PosH = 4.473639398641e+12 -1.415781279822e+11 -9.957820975908e+10
World[8].eph.PosN = 4.473639398641e+12 -1.415781279822e+11 -9.957820975908e+10
World[8].eph.VelN = 1.306517783315e+02 5.458394416560e+03 -1.158363505515e+02
World[9].PosH = 2.705989929332e+12 -4.496764028048e+12 -3.015895512943e+11
World[9].eph.PosN = 2.705989929332e+12 -4.496764028048e+12 -3.015895512943e+11
World[9].eph.VelN = 4.798223900754e+03 1.602296118134e+03 -1.559564813473e+03
World[10].PosH = 9.168768501236e+10 1.165991126682e+11 9.220791866979e+06
World[10].eph.PosN = 3.334711413438e+08 1.220938526592e+08 6.298426933558e+07
World[10].eph.VelN = -4.282760256918e+02 8.788149668665e+02 4.829576257736e+02
World[11].PosH = 1.618980679711e+10 2.326152612588e+11 4.452616982597e+09
World[11].eph.PosN = -2.739507237407e+06 -9.040935293393e+06 1.771794207835e+05
World[11].eph.VelN = 2.024194199277e+03 -6.426501388566e+02 1.769441825873e+00
(...a lot more World[x] entries ...)
[EOF]
2024-318-18:38:34.500000000
SC[0].B[0].wn = -1.748865083681e-03 -6.927475621347e-03 2.421122225958e-03
SC[0].B[0].qn = 4.985869992252e-01 2.909902747759e-01 6.853904088098e-02 8.136572153337e-01
Oh hey, when I turned the server from TXRX to simply RX only it's stable and appears to have accepted the packet.
Amazing!