Wireshark · Display Filter Reference: Modbus/TCP

Field name	Description	Type	Versions
mbtcp.cannot_classify	Cannot classify packet type. Try setting Modbus/TCP Port preference to this destination or source port	Label	2.2.0 to 4.4.2
mbtcp.len	Length	Unsigned integer (16 bits)	1.8.0 to 4.4.2
mbtcp.modbus.and_mask	AND mask	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.bit_cnt	bit count	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.byte_cnt	byte count	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.byte_cnt_16	byte count (16-bit)	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.conformity_level	Conformity Level	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.data	Data	Byte sequence	1.8.0 to 1.8.15
mbtcp.modbus.diagnostic_code	diagnostic code	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_count	event count	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_msg_count	message count	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_recv_broadcast	Broadcast Received	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_recv_char_over	Character Overrun	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_recv_comm_err	Communication Error	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_recv_lo_mode	Currently in Listen Only Mode	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_send_lo_mode	Currently in Listen Only Mode	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_send_read_ex	Read Exception Sent	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_send_slave_abort_ex	Slave Abort Exception Sent	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_send_slave_busy_ex	Slave Busy Exception Sent	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_send_slave_nak_ex	Slave Program NAK Exception Sent	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_send_write_timeout	Write Timeout Error Occurred	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.ev_status	status	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.exception_code	exception code	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.func_code	function code	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.mei	MEI type	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.more_follows	More Follows	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.next_object_id	Next Object ID	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.num_objects	Number of Objects	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.object_id	Object ID	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.object_str_value	Object String Value	Character string	1.8.0 to 1.8.15
mbtcp.modbus.objects_len	Object length	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.or_mask	OR mask	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.read_device_id	Read Device ID	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.read_reference_num	read reference number	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.read_word_cnt	read word count	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.reference_num	reference number	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.reference_num_32	reference number (32 bit)	Unsigned integer (32 bits)	1.8.0 to 1.8.15
mbtcp.modbus.reference_type	reference type	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.unit_id	unit identifier	Unsigned integer (8 bits)	1.8.0 to 1.8.15
mbtcp.modbus.word_cnt	word count	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.write_reference_num	write reference number	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.modbus.write_word_cnt	write word count	Unsigned integer (16 bits)	1.8.0 to 1.8.15
mbtcp.prot_id	Protocol Identifier	Unsigned integer (16 bits)	1.8.0 to 4.4.2
mbtcp.trans_id	Transaction Identifier	Unsigned integer (16 bits)	1.8.0 to 4.4.2
mbtcp.unit_id	Unit Identifier	Unsigned integer (8 bits)	1.10.0 to 4.4.2
modbus_tcp.and_mask	AND mask	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.bit_cnt	bit count	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.byte_cnt	byte count	Unsigned integer (8 bits)	1.0.0 to 1.6.16
modbus_tcp.byte_cnt_16	byte count (16-bit)	Unsigned integer (8 bits)	1.0.0 to 1.6.16
modbus_tcp.data	Data	Byte sequence	1.6.0 to 1.6.16
modbus_tcp.exception_code	exception code	Unsigned integer (8 bits)	1.0.0 to 1.6.16
modbus_tcp.func_code	function code	Unsigned integer (8 bits)	1.0.0 to 1.6.16
modbus_tcp.len	length	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.or_mask	OR mask	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.prot_id	protocol identifier	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.read_reference_num	read reference number	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.read_word_cnt	read word count	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.reference_num	reference number	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.reference_num_32	reference number (32 bit)	Unsigned integer (32 bits)	1.0.0 to 1.6.16
modbus_tcp.reference_type	reference type	Unsigned integer (8 bits)	1.0.0 to 1.6.16
modbus_tcp.trans_id	transaction identifier	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.unit_id	unit identifier	Unsigned integer (8 bits)	1.0.0 to 1.6.16
modbus_tcp.word_cnt	word count	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.write_reference_num	write reference number	Unsigned integer (16 bits)	1.0.0 to 1.6.16
modbus_tcp.write_word_cnt	write word count	Unsigned integer (16 bits)	1.0.0 to 1.6.16