42
If a TCP socket is open, but the remote Modbus TCP slave/server
returned exception 0B (hex)
DISABLE MODBUS/TCP PIPELINE
Typically a Modbus master issues a query and waits for a response before issuing
another. However, when using Modbus/TCP, multiple queries can be issued and the
MES1A/B will buffer them in a “pipeline”. The MES1A/B can fetch each query one at
a time, and respond. In some situations this is useful, but in others the sequence of
query/response can get out of sync (especially if any queries or responses are lost).
The Disable Modbus/TCP Pipeline setting allows you to decide how you want the
system to operate.
Setting this field to 1 = No configures the MES1A/B to allow pipeline
operation. This is considered the safest default setting. It is
recommended that you choose this option unless you are experiencing
problems.
Setting this field to 2 = Yes configures the MES1A/B to always fetch the
latest request from the TCP buffer (discarding all older requests).
CHARACTER TIMEOUT
Although Modbus/RTU specifies a 3.5 character time out period between characters,
the Character Timeout field allows you to set a custom value for this field.
If you set this field to 0, the MES1A/B will automatically calculate a
minimum timeout based on the baud rate being used.
Although you can set this field to any value between 1 milliseconds and
6959 milliseconds, a recommended safe value for general use is about
50 milliseconds (which is the default value).
