
Modbus Commands
2-32
SIMATIC TI505/TI500 MODNIM User Manual
Modbus Function Descriptions (continued)
T
able 2-6
Event
Byte T
ypes
Event Byte Bit Definitions
Slave Bus Receive. Byte
stored on receipt of message
Bit 0 – Reserved
Bit 1 – Set if communications error
Bit 2 – Reserved
Bit 3 – Reserved
Bit 4 – Set if character overrun
Bit 5 – Set if in Listen Only mode
Bit 6 – Set if Broadcast
Bit 7 – 1
Slave Bus Transmit. Byte
stored when message sent
Bit 0 – Set if an exception (1–3) is sent
Bit 1 – Set if secondary abort exception (6) is sent
Bit 2 – Set if secondary busy exception (6) is sent
Bit 3 – Not used
Bit 4 – Set if write timeout occurred
Bit 5 – Set if in Listen Only mode
Bit 6 – 1
Bit 7 – 0
Entered Listen Only
Mode. Byte stored when
LOM mode entered
Bit 0 – 0
Bit 1 – 0
Bit 2 – 1
Bit 3 – 0
Bit 4 – 0
Bit 5 – 0
Bit 6 – 0
Bit 7 – 0
Initiate Communications
RESET. Complete log is set
to zeros.
Bit 0 – 0
Bit 1 – 0
Bit 2 – 0
Bit 3 – 0
Bit 4 – 0
Bit 5 – 0
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