3.4.7Modem Booster
How the Parameter Applies to the BM85
The Modem ooster applies to M85 Modbus ports that will be configured as Network ports You will need this information for any port you will be using as a Modbus Network port
The parameter does not apply to a port that is being configured as a single Master or Slave device port You can bypass the information below for any port you will be using as a single Master or Slave port
The Purpose of the Parameter
The Modem ooster parameter determines how the M85 will handle
Modbus commands to networked slave devices at a Modbus port
When the M85 receives a command that is addressed to a slave device at a Modbus network port, a response is expected from the slave device Two methods are available for handling the response, defined by the function code in the command issued by the master The two kinds of commands are:
V `Suspend' Transactions (Function Code 126) With this type
of command, the slave device will send a response after it completes the action requested in the command The master device waits for the response, and therefore other commands on the Modbus network cannot be processed until the slave's action has been completed and its response received Other transactions intended for the port must remain pending until that time Some.commands, such as `start' and `search' commands from a Modicon P230 programming panel to a slave controller on the Modbus network, can take a relatively long time for processing in the controller, in the range of 15 seconds to 2 minutes
V `Polling' Transactions (Function Code 13) With this type of command, the slave will send an acknowledgement of receipt of the command, and must be polled later by the master device to determine if the requested action has been completed The command acknowledgement frees the Modbus network for processing messages to other devices on the port The M85 will poll the slave device periodically to determine if the command action has been completed It will then send the final response to the originating device
The Modem ooster parameter allows you to specify which of the two methods will be used at the M85 Modbus port
34 Configuring the Modbus Models | 31007492 |