Schneider Electric Modbus Plus Network Bridge Multiplexer none - Manual (Page 42)

Configuring the Modbus Models 31007492 32
3.4.6 Link Timeout
The Purpose of the Parameter
Link timeout is the maximum time you will allow for a slave device to
respond to a command issued at the BM85 Modbus slave port. In your
application, if the timeout value is exceeded, a `slave device down` error
code will be returned by the program function initiating the command to
the device.
If the timeout value is too short, slower devices may not have time to
respond normally to their commands, resulting in apparent errors at the
device. If the value is too long, and a device fails to respond, your
application will have to wait until the timeout occurs before handling the
device condition or using the port again.
A value should be set to handle the slowest device at the port, without
excessive delay. The value should accommodate the sum of the
following:
V serial communication time
V slave device processing time: for example, controller scan time
V BM85 processing time for port transactions, approximately 4 ms.
Setting the Parameter
You set each port's timeout parameter as a value in the range 1 ... 3000.
The timeout value represents multiples of 100 milliseconds.
For example, a parameter of 10 specifies a link timeout of 10 x 100 ms,
or one second.