RS485 / Modbus - can this work

I’m looking for a way to measure power consumption per circuit. I found http://bg-etech.de/os/product_info.php/products_id/201 which offers a modbus interface. Now I don’t know anything about modbus, and it seems that the IPSymcon-supported modbus is ‚modbus tcp rtu‘ which is different from the interface this meter offers, as far as I understand.

So I’m wondering, is it possible to use something like http://usb-rs485.eu/WebOrder.asp?focus=STISO485, just plug that into my ipsymcon server, connect the power meter above to it, then use a serial port and register variable in ipsymcon to read values? Would I have to calculate e.g. modbus checksums myself, or can I re-use any of the ModBus_xxx functions in IPSymcon?