RxPDO sent value is updated slowly

Hello and thanks a lot for your work!

I’ve successfully configured a RxPDO to be sent every 10ms. The sent value should be different at any transmission, but I see on the slave node a received value that change every 3 or 4 sent PDOs (30-40ms). Sending an SDO instead of a PDO I was able to send a different value every 1ms. (You can see the related code commented below.)

I leaved my previous tries as commented code.

Am I missing something?

Thanks in Advance!

`

s60.rpdo.read()
s60.rpdo[1].clear()
s60.rpdo[1].add_variable('Target position')
s60.rpdo[1].enabled = True
s60.rpdo.save()
s60.rpdo[1]['Target position'].raw = (7*6000).to_bytes(4, 'little')
s60.rpdo[1].start(0.01)

s60.nmt.state = 'OPERATIONAL'
print("Gone Operational")

network.sync.start(0.001)


starttime = time.time()
oldtime = time.time()
while True:
	newtime = time.time()
	if newtime-oldtime>0.0005:
		cosminus1 = math.cos(1.0*(newtime-starttime))-1
		feeds = int(6000 * cosminus1 * 3.3 + 42000)
	#print(feeds, '@ timesector:', newtime-oldtime)
	#s60.sdo.download(0x607A,0,feeds.to_bytes(4, 'little'))		#MF: Target position

		#s60.rpdo[1].setdata = feeds.to_bytes(4, 'little')
		#s60.object_dictionary['Target position'].raw = feeds.to_bytes(4, 'little')
		#s60.rpdo[1].update()
		#s60.rpdo[1]['Target position'].raw = feeds.to_bytes(4, 'little')
		s60.rpdo[1]['Target position'].set_data(feeds.to_bytes(4, 'little'))
		oldtime = newtime

`

[christiansandberg]

Ixxat utilizes the hardware for periodic transmission which improves timing between messages, but unfortunately it does not provide a way to update the data after it has started. Therefore the message needs to be stopped and recreated every time the data is changed. This is probably very expensive and probably why you have such problems.

I don’t have a solution for you but implementing the periodic transmission yourself might be one.

[af-silva]

@Matiu-f

Yes, but depending on your configuration it will only be executed at sync message. A think the way the framework it’s build, at sync it will grab the data and transmit it, so you should be seeing data being sent and updated at the frequency you configured at network.sync.start()

You have also to check the CAN interface configuration and the Bus speed supported, for instance I use SocketCAN at 1000 Kbit/s with with kvaser …

s60.rpdo.read()
s60.rpdo[1].clear()
s60.rpdo[1].add_variable('Target position')
s60.rpdo[1].enabled = True
s60.rpdo.save()

s60.rpdo[1]['Target position'].raw = (7*6000).to_bytes(4, 'little')
s60.rpdo[1].start(0.01)

network.sync.start(0.01) # 10 milliseconds 

s60.nmt.state = 'OPERATIONAL'
print("Gone Operational")

starttime = time.time()
oldtime = time.time()

while True:
	delta = int(starttime  * 1000) - int(oldtime * 1000)
        if delta < 10:
	    continue
	cosminus1 = math.cos(1.0*(newtime-starttime))-1
	feeds = int(6000 * cosminus1 * 3.3 + 42000)
	s60.rpdo[1]['Target position'].set_data(feeds.to_bytes(4, 'little'))
	oldtime = newtime