Siemens 500 NIM - Manual (Page 69)

NIM Primitives 4-16 SIMATIC TIWAY I Series 500 NIM User Manual
Data Element Types and Formats (continued)
Table 4-4 Basic Data Unit Format (continued)
TT Data Element Type
Length
(in bytes)
** 43 or 83 Analog Alarm Sample Rate 4
** 44 or 84 Analog Alarm Setpoint 4
45 Analog Alarm Variable Flag* 2
46 Analog Alarm Control Flag 4
** 47 or 87 Analog Alarm Error* 4
** 48 or 88 Analog Alarm P.V. High High Alarm 4
** 49 or 89 Analog Alarm P.V. Low Low Alarm 4
** 4A or 8A Analog Alarm Rate of Change Alarm 4
* These TT types are read-only data elements.
# This TT type is a write-only data element.
** Format
2x, 3x, and 4x = IBM format
6x, 7x, and 8x = IEEE format
NOTE: See Appendix B for a definition of TT 2x, 3x, 4x, 6x, 7x, and 8x
floating point representation.
TT = 3, 4, 5 = Discrete (1 byte)
1 2 3 4 5 6 7 8
MSB LSB
X value Bit Definition
0 Off
1 On
0 0 0 0 0 0 0 X
Figure 4-4 Discrete Data Element Format