Rockwell Automation 61C345 4 Input 4-20mA Analog Rail Module - Manual (Page 14)

2Ć4
+10.000 V
4 to A/D
converter
277.778 W
32mA
(  250 W )
IĆIN
IĆCommon
Figure 2.2 Ć Typical Input Circuit
The Analog Rail module is factory calibrated and requires no
offset/gain adjustment. All four analog input channels are referenced
to the same common. This common is isolated from both the
external power supply and the I/O port connection.
The module incorporates extensive diagnostics. In Rail mode, check
bits are monitored for accuracy on every transfer of data between
the processor and the module. In Local Head mode, parity bits are
monitored for accuracy on every transfer of data. A Rail fault LED on
the processor, Remote Head, or Local Head will be illuminated if the
check bits or parity bits are wrong and all transmission will stop after
n retries, where n is a value determined by the host's software
(average n = 4 for AutoMax; AutoMate n = 2).
In the event of a rail fault, the COM OK" LED on the module will go
off. If any power required by the module, i.e., the +5 Volts from the
I/O port required for communication, the external power supply, or
the power required by the Analog input section, is not within
specified limits, the PWR OK" LED will go off.