Advanced Function Programming 3-31
SIMATIC 505–2557 Installation and Operation Guide
3.10 Items Unique to the SIMATIC 505–2557 Module
Items
unique to the SIMA
TIC 505–2557 RTD Input Module.
Open
RTD Status Bits: WX55
Figure 3-18 Open
R
TD Status Bits
The bits returned in WX 55 indicate an open RTD for a particular channel.
Floating
Inputs
If
no RTD is connected to an input channel the value returned to the PLC is
unpredictable.
The inputs on the SIMATIC 505–2557 are floating; that is there are no
internal pull up or pull down circuits to force the input to either a maximum
or minimum temperature value. Unused inputs therefore should be
terminated by shorting the V+ and G terminals together
.