Instruction Manual
Tek-LCD 7801C
www.tek-trol.com
Technology Solutions
61
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The available functions depend on the I/O cards insta
lled and the controller’s configuration.
•
Alarm Reset: The alarm condition is cleared, allowing the alarm to trigger again based on
input.
•
Acknowledge: The input must cross the reset point to trigger new alarm after it has been
acknowledged.
6.40
Modbus
Functionality
•
The Tek-LCD 7801C supports Modbus RTU, Modbus ASCII, Enron Modbus, and Ethernet Modbus
TCP/IP. The Server mode is a standard Tek
-LCD 7801C feature; it responds to requests and
accepts writes from a Modbus client.
•
The Client mode can request process variables from server devices; the input variables can be
scaled, combined with other variables using math functions, and they can be written to other
server devices using the Modbus output functions.
•
The Snooper mode can listen and read the process variables being transmitted on the RS-485
bus without causing any disruptions to the network.
•
The Spoofer Modbus output is used to replace Modbus devices that have been removed from
the network; there is no need to make changes to the Modbus client’s configuration.
6.41
Setup Modbus Inputs (Server)
The Modbus Server mode is a standard feature. The controller can accept up to 199 Modbus inputs
sent by a Modbus Client. The inputs can be used as the source for channels, math functions, alarms,
relay control, etc.
•
Enter Modbus Input tag
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Type: Select the data type The register number is displayed to the right
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Decimals: Number of decimals
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Units: Select units or enter custom unit
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Break: Value or condition for comm. break
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Timeout: Select timeout to detect break
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Input Action: Select action when new value is received (e.g. Add to Total 1 the value
written)
