Hi!
I have some problems regarding the transmission of downlink frames in ping slots, when running class B on my end device.
I have the following versions installed on my raspberry pi, which is the gateway:
hirp/stable 1:20200227+py3+20200213-3 all
chirpstack-application-server/stable,now 3.17.7 armhf [installed]
chirpstack-gateway-bridge/stable,now 3.14.2 armhf [installed]
chirpstack-geolocation-server/stable 3.3.1 armhf
chirpstack-network-server/stable,now 3.16.3 armhf [installed]
chirpstack-packet-multiplexer/stable 3.1.0 armhf
I have setup my end device for class B and the pingSlotChannelReq MAC-command has been sent and the network has also received the pingSlotChannelAns, where both the frequency and data rate were OK.
However, when I queue downlink payloads, which are not confirmed downlinks, the payloads never get sent to the end device.
Is this due to the downlink queue not being intended for the ping slot down links? Or is it perhaps because I have not done the setup correctly?
I have read the following:
“Once in the state of a beacon lock, the device negotiates its ping-interval. ChirpStack Network Server is then able to schedule downlink transmissions on each occurring ping-interval.”
From: Device-classes - ChirpStack open-source LoRaWAN<sup>®</sup> Network Server
Is it correctly understood that this means the chirpstack network server needs to get a “PingSlotInfoReq” uplink in order for it to begin to transmit downlink payloads in the ping slots?
I hope someone here will be able to help me with my issue 
Best regards.