CTI 2550-A, Installation And Operation Manual

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6 C T I 2550-A Installation and O peration G uide
Figure 6 Voltage Input Limits (Unipolar)
Figure 7 Voltage Input Limits (Bipolar)
1.8.1 Unipolar Mode
Signals falling below the lower limits in 0 to 5V Input Mode or 0 to 10V Input Mode are translated
into a digital word that includes the addition of Bit 16 to indicate an overrange or underrange condition.
Note that although the digital word may approach zero as the analog input signal approaches the
minimum given range, the digital word will never actually be zero. In fact the underrange capability of
any channel in Unipolar Mode may produce a negative value to the PLC for a number of counts before
the underrange bit is set.
1.8.2 Bipolar Mode
In Bipolar Mode signals above or below the upper and lower limits in the -5 to +5VDC or
-10 to +10VDC range are translated to a digital word and also utilize the overrange and underrange bit.
The actual limit for each channel will vary from channel to channel as described above.