Cutler-Hammer D320 PLC, User Manual

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D320 PLC User's Manual
F11.14 RESERVED
This flag is not currently defined for communications and should not be used or referenced.
F11.15 ENABLE AUTOMATIC CRC
UDCP Mode. The CPU is capable of automatically generating a CRC-16 checksum on
communications sent and received. When this flag is turned on, the CPU automatically calculates and
appends a CRC-16 checksum to the transmit data stored in the Transmit Data Buffer. Additionally,
when data is received, the CPU checks the Receive Data Length (SR371), calculates a CRC-16 on the
received data, and compares it to the data received at the end of the receive message. If the CRC does
not match, the Receive Error Flag (F11.7) is set.
F12.8 ENABLE USER-DEFINED (UD) COMMUNICATIONS
Setting this flag enables port 2 of the CPU to support ASCII/Binary transmit and receive functions. It
also necessarily disables the standard D320 Program Loader Port protocol support on the port.
F12.9 ENABLE MODBUS RTU SLAVE COMMUNICATIONS
When this flag is set, port 2 of the CPU is configured to support the open industry-wide MODBUS
RTU slave protocol. Peripheral devices can communicate to the D320 CPU using the standard
MODBUS RTU communications for reading and writing data. Setting this flag disables the standard
D320 Program Loader Port protocol support for port 2.