User Manual

Siemens Building Technologies PROFIBUS DP/P-bus link
Building Automation User's guide 1-3
1.4 Features
On the P-bus side, the DP/P-bus link is enabled for the local bus (a P-bus cable up to 50m in
length). On the Profibus side, distances of up to 1000m can be covered.
The number of DESIGO I/O modules per DP/P-bus link depends on the following conditions:
Maximum 50 DESIGO I/O modules are supported
• Up to 128 load units
• Max. 216 input bytes
• Max. 216 output bytes
• The maximum total must not exceed 216 bytes
• Programmable Profibus DP address spaces 1…99
The following example shows how to determine the number of load units and address space:
With the module mix shown in the table below, the totals are 9 load units and an address space
of 6 input bytes and 9 output bytes. For the maximum configuration, a further 119 load units and
an additional 201 input/output bytes are available for the I/O modules.
DESIGO
I/O modules
Load units Input bytes Output
bytes
PTM1.2D20 DIGITAL INPUT 2 x DI
potential-free contacts DC 22 V
2 1 0
PTM1.4QD DIGITAL OUTPUT 2 x DO;
with feedback
4 1 1
PTM1.2P100 ANALOG INPUT 2 x AI; 0…250 ohms
Pt100/Ni100 (4-wire)
2 4 0
PTM1.4Y10S ANALOG OUTPUT 4 x AO
0…10V
1 0 8
Total 9 6 9