Digital BW, The Print

Apologies if this is a bit off topic. I've been trying to link the 810 to my
PC but can't seem to get the two to communicate. I'm using a standard serial
25-pin to 9-pin modem cable but suspect that possibly the pin configuration
is different. In the manual it says that a 'DP25S' type cable is required
but noone here in the UK seems to know what that is. 

Does anyone have any information on this?

Thanks
Howard