Siemens Simatic S7-400 - Manual (Page 381)

Interface Modules
6-19
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Function
The interface module pair IM 460-4 (send IM) and IM 461-4 (receive IM) are used
for a remote link of up to a maximum 605 m (exactly: 600 m plus inputs/outputs of
1.5 m in the line).
Parameterization
Using the DIP switch on the front panel of the module, you must set the number of
the mounting rack in which the receive IM is installed. The permitted range is
1 to 21.
If required, you can change the distance setting for the line on the programming
device using STEP 7.
The default setting for the distance is 600 m.
Ensure that the distance corresponds as closely as possible to the current length
(the sum of all the connecting cables per line) as this will accelerate data
transmission.
Note
The distance set must always be longer than the actual length of cable per line.
Setting/Changing the Number
Proceed as follows:
1. Put the switch of the power supply module in the EU in which you want to make
the change in the position (Output voltage 0 V).
2. Enter the number using the DIP switch.
3. Switch the power supply module on again.