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1MAC052634-MB D
3.1.2.2
615/620 series ANSI
Communication Protocol Manual
Client's write authority
The registering of a Modbus client affects the client's write authority and the reading of
latched Modbus data.
The TCP write authority parameter can be set to three different states:
• 0 = No write authority for any Modbus TCP/IP client
• 1 = Write authority only for registered Modbus TCP/IP clients
• 2 = Write authority for all Modbus TCP/IP clients
The possible blocking of write operation does not include the selection write operation that
has to be done to read out Modbus event and fault record structures.
Modbus TCP/IP diagnostic counters
Modbus TCP/IP counters can be viewed via the LHMI path Monitoring >
Communication > Modbus > Ethernet.
Counters related to the possible Modbus TCP/IP instances 1...5 have the suffixes 1...5 (N).
The counters show the complete Modbus protocol link frames and Modbus errors. The
Ethernet communication driver maintains its own counters for lower level communication
diagnostics.
Table 4:
TCP/IP diagnostic counters
Counter
Description
Received frames
Total amount of received Modbus frames.
N
Transmitted
Total amount of transmitted Modbus responses.
frames N
Transmitted Exc
Total amount of exception responses 1 and 2. These exception responses usually
A N
reveal configuration errors on the Modbus client's side.
Transmitted Exc
Total amount of exception responses 3. These exceptions reveal the IED application
B N
level rejections.
Status N
Shows the value "True" if the TCP/IP or serial instance is in use. This means that a
Modbus client has connected to the TCP socket and Modbus TCP messages are
received regularly at least with a 30 second interval or faster. In all other cases this
value shows "False". Resetting of all diagnostic counters in the instance N is done by
writing value "True" into this same Status N object.
The counters and status of an instance N are reset when the client makes a TCP socket
disconnection or if the TCP socket connection keep alive times out.
The common (instance independent) Modbus TCP/IP diagnostic counters can be reset
separately by writing the value 0 into them.
Vendor-specific implementation
Section 3
13
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