Siemens 505-2557 installation and operation guide Operating Modes

1.1Operating Modes

	The SIMATIC 505±2557 Sixteen Channel RTD Input Module is a member of
	Siemens's family of I/O modules compatible with the SIMATIC 505 series
	programmable controllers. The SIMATIC 505±2557 is designed to translate
	10 Ohm copper, 100 Ohm platinum and, 120 Ohm nickel RTDs or millivolt
	input signals into scaled digital words which are then sent to the
	programmable controller (PLC).
	The SIMATIC 505±2557 RTD Input Module features built±in independent
	two, three, or four lead compensation for each RTD input. Support for other
	RTD types is available through special request from the factory. For
	technical assistance, contact your Siemens Energy & Automation, Inc.,
	distributor or sales office.
Asynchronous	The module operates asynchronously with respect to the PLC; a scan of the
Operation	PLC and input sampling of the module do not occur at the same time.
	Instead, the module will translate all inputs in one module update (20
	milliseconds maximum) and store the translated words in a buffer memory.
	The PLC retrieves the stored words from the module buffer memory at the
	start of the I/O scan.
Compatability with	The SIMATIC 505±2557 has been tested and is compatible with the
Immediate I/O	Immediate read function of the SIMATIC 545 and 555 PLC.
100 Ohm, 10 Ohm,	Each of the module's 16 channels may be configured to receive either a 100
120 Ohm RTDs, or	Ohm platinum RTD or a 120 Ohm nickel RTD or a 10 Ohm copper RTD
Millivolt Inputs	input signal (two, three or four wire) or a DC voltage signal ranging from 0
	to 100 millivolts. Selection of 10 Ohm, 100 Ohm or 120 Ohm RTDs or
	millivolts are made via internal switch and jumper settings.

1-2 Description SIMATIC 505±2557 Installation and Operation Guide