S7-SoftPLC:Zero modem cable

Sub.-D case			Sub.-D case
Connector			Connector
9 Pin	25 Pin		9 Pin	25 Pin
1	---	-----------no connection-----------	1	---
2	3	-----------------------------------------	3	2
3	2	-----------------------------------------	2	3
4	20	-----------------------------------------	6	6
5	7	-----------------------------------------	5	7
6	6	-----------------------------------------	4	20
7	4	-----------------------------------------	8	5
8	5	-----------------------------------------	7	4
9	---	-----------no connection-----------	9	---
housing	housing	----------------shield----------------	housing	housing