name:          	- RSDO
description:   	- Read data from the can controller

creation date: 	- 18/6 -2002 ISAgraf
                  29/12-2002 Straton

author:        	- Rune Rafn SP-Teknik APS.

call:  	        - ANALOG board: Specifies witch board in target data is sent to. 
                  Hilscher hardware supports up to 4 cards pr. target. Typically 0
                - ANALOG Node: Specifies witch node on the can bus the data is for. CanOpen support up to 127 nodes.                     
                - ANALOG Index: Index in node to read from.
                - ANALOG Subindex: subindex for the specific index, to read.
                - ANALOG Datasize: Length of data field in the specific subindex, in bytes. possible values: 1,2 and 4. (If not sure, use 4)
                - ANALOG Timeout: Max time to wait for function in milliseconds. 
                  Timeout is used at least twice in this function. Max 100ms.

return:       - ANALOG Data: Data read from node.
                     Returns -1 if read fails.

prototype:   -

notes:       -

example:     - read data from index 24743, subindex 0 in node 2 connected 
                    to board 0, would look like this: data := RSDO(0,2,24734,0,4,100)all values are in decimal.
                    The function return the value of the specific subindex or -1 if function fails.