Shared device access – SATEC ETC2002 User Manual
Page 16
Chapter 3 Operating the ETC2002
Using the ETC2002
16
ETC2002 Network Communicator
The ETC2002 has two options for routing messages over the slave networks,
depending on whether the device routing table is defined in your ETC2002 or
not.
The first option uses implicit rules that identify the device location statically
upon the device address. The following table shows how the messages are
routed through the COM4 and COM5 serial ports depending on the port
usage. When using non-standard communication protocols, all messages
are routed to the COM4 port.
Port COM5
Unused
COM4 Master +
COM5 Serial
COM4 Master +
COM5 IP-Link
COM4 Slave +
COM5
COM4 Master 1-247
1-32
216-247
-
COM5 - 33-247
1-215
1-247
The second option uses the device routing table. It is available starting with
V21.5.4. The routing table explicitly identifies the target network for every
individual device connected to the ETC2002. For serial and wireless devices,
it specifies a serial port to which the device network is connected. For
Ethernet devices, it allows you to specify the device’s IP address on the
Ethernet network.
To use the device routing table:
1. Specify a routing path for every device connected to the
ETC2002 gateway. Specify the IP address for every Internet
device and the target serial port for every serial and wireless
device connected to the ETC2002. See
in Chapter 5 for information on programming the
device routing table.
2. Enable the routing table in your ETC2002 via the ETC2002
Gateway Options Setup (see
Chapter 5).
Shared Device Access
Shared device access allows several clients to simultaneously access the
slave device’s registers either for reading or writing. It is enabled by the
default, so different clients can poll registers in the same device without
collisions that are normally resolved by the ETC2002.
However, accessing a file in the device at the time when another client is
reading data from that or another file in the same device could destroy file
buffers such that both clients may receive corrupted data.
To avoid possible collisions, the ETC2002 offers you two options:
1. First, you can entirely disable shared device access so that the
ETC2002 rejects any additional requests addressed to a device
that is being accessed by another client. In this event, the
ETC2002 returns an exception response with the error code 10
“Gateway is busy” until the first client closes the session or points
to a different device. See
Chapter 5 on how to enable or disable shared device accesses in
your ETC2002.
2. The second option uses the device routing table for defining a
device-sharing policy. Shared device access should be enabled
in the ETC2002 (see
and device-sharing rules should be selected for each individual
device. In this event, only protected registers, which are defined
by a selected access rule, are blocked for shared accesses while
others are always available for all clients. See
in Chapter 5 for information on
programming the device-routing table.