How many bytes can xbee.transmit method send?


My equipment is an XBee 3 RF Zigbee module which I program using Micropython.
I have created a (big) file full with data, which i want to wirelessly transmit, using the xbee.transmit() method.

So, I would like to ask how many bytes can the transmit method send? In other words, what is the max size of the payload passed in transmit method?
xbee.transmit(dest, payload[, source_ep][, dest_ep][, cluster][, profile][, bcast_radius][, tx_options])

Thanks in advance

Up to 255 bytes (One modbus packet).