Dynalco SC-2124M Scanner/Monitor - Manual (Page 16)

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4.0 Standard Operation
After power-up, the SC-2124 performs all standard SCANNER operations continually. These
operations include scanning all enabled analog input channels to update the channel
readings; monitoring channel inputs for Open Thermocouple, ALARM, or SHUTDOWN TRIP
conditions; performing Dynalink or Modbus communications to external devices.
To update all scanner channels, the SCANNER reads all enabled channels’ current analog
input readings. These readings are performed continuously and sequentially for all enabled
scanner channels. Current channel measurement readings are averaged with the previous
value to update the current analog input channel value.
The SCANNER then monitors each channel’s value compared to the channel’s configured
ALARM and SHUTDOWN thresholds. If any of the channel thresholds is exceeded, the
channels are considered to be in a fault state, and the SCANNER TRIPs an ALARM or
SHUTDOWN (See Sections 4.3 & 4.4). In addition, the SCANNER monitors all
thermocouple channels for Open Thermocouple detection. If any thermocouple channel is
open, the SCANNER labels that channel as open and displays ‘OPEN TC’ instead of that
channel’s current analog input reading. Detection of an open thermocouple on any scanner
channel may also result in an ALARM or SHUTDOWN (See Sections 4.3, 4.4, & 3.1.2.1).
Lastly, the SCANNER continually communicates with any external devices that initiate
communication and request SCANNER parameters. The SCANNER is capable of
communicating by Dynalink and Modbus. Only one serial communication port is available on
the SC-2124; thus, only one type of communication may occur on the port at any one time
(See Section 3.1). Dynalink would be used primarily while the SCANNER is being
configured using Dynalco Controls HOST software. Modbus communication would be used
to connect the SCANNER to other devices that communicate via Modbus.