Operation And Configuration; Asynchronous Operation; Immediate I/O Compatibility; J, K, R, S, T, E, Or L Thermocouples - Siemens SIMATIC 505 Installation And Operation Manual

1.2

Operation and Configuration

Asynchronous
Operation
Immediate I/O
Compatibility
J, K, R, S, T, E, or L
Thermocouples

Digital Word Map

SIMATIC 505–2556 Installation and Operation Guide
The module operates asynchronously with respect to the PLC; a scan of the
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 (24
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.
The SIMATIC 505–2556 has been tested and is compatible with the
Immediate Read function of the SIMATIC 545 and 555 PLC. The SIMATIC
505–2556 is compatible with 545 and 555 PLCs. It is compatible with the
525 PLCs in 16WX mode only.
Each of the module's sixteen channels may be configured to receive either
J, K, R, S, T, E, or L thermocouple input signals or a DC voltage signal
ranging from –55 to +55 millivolts. Selection of thermocouple type or
millivolts are made via internal DIP switch settings and hardware jumpers
(see Sections 2.4.1 and 2.4.2).
Thermocouple and/or millivolt signals are translated into a 14–bit digital
word. Since the PLC requires a 16–bit input word, the 14–bit value from the
converter is placed into a 16–bit word for transmittal to the controller. As
shown in Figure 1-2, of the two bits not used for the digital word, one is
used to show the sign of the word, while the other is used to note values
which are "overrange."
Figure 1-2 Word Input to the PLC from the Module
Description 1-3