Arduino + Digi module slow communication

I am creating a wireless control using the xbee shield on top of an arduino as the controller, and a PC application (Processing) + Xbee module as interface.

I managed to get a communication up and running, even using zigbee.

My problem is that in my PC application has a couple of sliders for setting some remote values on the controller. It works, but sometimes it takes very long (up to 10s) before I receive an acknowledge from my controller.

If I remove the xbee shields and do a direct serial communication it goes all very well. I use a baudrate of 19K2.

can anyone help?

Karl

When you move the slider, does the attached XBee board flash it's TX light right away?

Does the receiver flash it's RX light right away?

What code is loaded on the Arduino? Does it involve delays or computationally intensive processing?

the transmit and receive on the host xbee module are flashing the moment data is going out as well as when data is comming in.

the only thing that needs to be done is to interpret the incomming bytes, and if a certain CMD is passing by I sets the PWM value of one of the analog outputs.

I use a xor function for generating a checksum, is that time consuming?

On the other hand, when I replace the zigbee link by a serial link, it is all running very smoot.

What baud rate are the xbees talking at?

I started with 9600, but now I am using 19200.

Kind regards, Karl.