The string data types are just where the two characters in a 16 bit word are reversed or not i.e. DSH/DSL is how the bytes are presented Low byte first or high byte first.
Mitsubishi use the low byte as the first char & the high byte as the next char
So in 1 mode is D100 = AB this means the characters are reversed in other words it will display on an HMI as BA, but the other mode is D100 = BA, so will display AB on an HMI, it is all to do with some systems like modbus have reverse bytes, The only way if you are sending strings is to try it as it will depend on how the other system handles them.
The NETH can do many things, normally, when you have a NETH system you set the card configurations for L Bits & L words there are used to send or read data, these are fixed when you configure the cards, so effectively each one has a fixed send/recieve area.
These must not overlap. It is a long time since I did one but that was on the old GXIEC IDE which I do not have on this PC, I will dig it out.
So for this it slaves automatically sends data from one PLC to the master
Where the master can send data both ways (seem to remember that you sometimes have to map the bits & words to get from one slave to the other).
Kepware can send data to the master via Ethernet, if this has to be passed to a slave then in Kepware when you configure the IP of the master you type in the IP i.e. 192.168.1.0:N<Net Number>:<PC Number>
Here is from the help file:
Q Series: Device IDs are specified as YYY.YYY.YYY.YYY:Nzzz:XXX or YYY.YYY.YYY.YYY:nzzz:XXX. The YYY designates the device IP address (each YYY byte should be in the range of 0 to 255). The zzz designates the Network Number of the target device and can be in the range of 0 to 255. The XXX designates the PC Number of the target device and can be in the range of 0 to 64 or 255 for the local PC.
Note: For a local connection, which is network 0, the network number can be omitted, resulting in the format YYY.YYY.YYY.YYY:XXX. For more information, refer to Multi-level
Multi level is to do with the passthough via the NetH, so if you want to send or recieve data from a slave i.e. 1 then it would be the :xxx i.e. slave 1 for example in a NETH network.
As the L & B registers that send/recieve data over the NetH is fixed, there is a way of sending other registers over from the master to a slave by using a function called JP_Send or JP_Rec, this is done in the master again cannot remember the details but in short:
NETH fixed LB & LW areas as configured in the NETH modules settings
NETH send & recieve functions in the PLC program using JP_SEND & JP_REC (usually D or R registers)
AND via Kepware to master ethernet passed via NETH to other station with the format YYY.YYY.YYY.YYY:YYY:XXX
Yes it takes some getting your head round, hope this helps.