Spectrum Controls 1769sc-HART Modules - Manual (Page 11)

Chapter 1: Module Overview
User’s Manual 0300217-03 Rev. A
1-3
9 write-on label for user identification tags
10 removable terminal block (RTB) with finger-safe cover
10a RTB upper retaining screw
10b RTB lower retaining screw
1.3.1 General Diagnostic Features
The module contains a diagnostic LED that helps you identify the source of problems that
may occur during power-up or during normal channel operation. The LED indicates both
status and power. Power-up and channel diagnostics are explained in Chapter 9
Diagnostics and Troubleshooting
.
Section 1.4
System
Overview
The modules communicate to the controller through the bus interface. The modules also
receive 5 and 24V dc power through the bus interface.
1.4.1 System Operation
At power-up, the module performs a check of its internal circuits, memory, and basic
functions. During this time, the module status LED remains off. If no faults are found
during power-up diagnostics, the module status LED is turned on.
After power-up checks are complete, the module waits for valid channel configuration
data. If an invalid configuration is detected, the module generates a configuration error.
Once a channel is properly configured and enabled, it continuously converts the output
command value (i.e. output words 0 to 3) to a proportional analog signal that is within the
output range selected for that channel.
Each time a channel command value is read by the output module, that data value is
tested by the module for an over-range or under-range condition. If such a condition is
detected, a unique bit is set in the channel status word. The channel status word is
described in Section 6.3 Input Data File.
Using the module image table, the controller reads the two’s complement binary
converted input data from the module. This typically occurs at the end of the program
scan or when commanded by the control program. If the controller and the module
determine that the data transfer has been made without error, the data is used in the
control program.