Filter
Top Products
75
6. Configuring the Gateway
Configuration
element
Description
Update mode This element is used to specify the transmission mode for the query on the Modbus
network. It takes one of the following four values:
- Cyclically................................. Default communication mode. The query is transmitted
periodically on the Modbus network (see “Update time”).
- On data change...................... The gateway transmits the query on the Modbus network
when at least one item of data from this query is changed by the Profibus-DP master.
So this is an
aperiodic communication mode. For instance, this is not the case with
the queries associated with “Transactions 1” and “Transactions 2” personalized
commands for the “TeSys U n°1” node of the gateway’s default configuration. These
queries are transmitted when at least one of the values of their output data
(addresses 16#0212 to 16#0217 or addresses 16#0218 to 16#0220D) is changed by
the Profibus-DP master. So all data from a single query must be updated by the
Profibus-DP master at the same time. If you are not certain whether your software is
able to update
all the output data from a query at the same time, we recommend
using “Change of State on trigger” mode for these two commands.
- Single Shot ............................. This transmission mode only allows a single Modbus
exchange for the whole of the time that the gateway is operating. This exchange
takes place just after the initialization of the gateway.
- Change of state on trigger...... With this
aperiodic communication mode, the Modbus
query is sent every time that the Profibus-DP master changes the value of an 8-bit
counter designated by the “Trigger byte address” element. Please see the description
of this element for further information about how to use this communication mode.
Update time
(10ms)
This element is only used by the gateway if “Update mode” is set to “Cyclically”. In this
case, it specifies the query’s transmission period on the Modbus network.
E.g.: With the ATS48, we will be using the configuration shown
opposite. The most notable points of this configuration are:
• On disconnection the data is reset on one of the two networks.
• 3 re-transmissions with a 100 ms timeout.
• Periodic communications with a cycle time set to 300 ms.