Introduction to MODBUS
The CTM-ONE and CTM-500 support 4 types of MODBUS:
MODBUS Master Gateway
MODBUS Slave Gateway
TCP Slave
Serial Slave
Self-Slave
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The mode setting of the serial port must be set to MODBUS for the RS232/RS485 port setting for MODBUS configuration to work even if no physical RS232 or RS485 devices are physically connected to the CTM device. |
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MODBUS configuration is available on the CTM local web interface under serial < modbus tab.
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The RS232 and RS485 tabs expand for specific MODBUS functionality. The CTM supports simultaneous RS232 and RS485 protocols so individual configurations can exist for either protocol.
For Ethernet-based MODBUS communication (TCP / RTU over UDP), either MODBUS RS232 or RS485 can be used.
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The “Mode” defines the Gateway Master or Gateway Slave operating state.
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Access must also be enabled for routing data via the wireless network when using MODBUS. This can be found under Configuration > Firewall > Service Access Rules.
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Make sure that field “Enable this rule” is checked off.
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