Shar Ing Data Be Tween The Mas Ter Oit, Slave Oit And Plc - Maple Systems Silver Series Installation And Operation Manual

Us ing EZware-500
6. Enter in the IP Address for the PLC in the Server IP Address: boxes. Note: Whatever the
network addresses are, the numbers (octets) in the first three boxes must match for the Local
IP and the Server IP.
7. Enter 255.255.255.0 for the Subnetwork Mask.
8. If there is a router that will be between the OIT and the PLC, enter the router IP address in
the Default Route IP address section.
To configure the Slave OIT if there is an Ethernet connected Slave OIT Unit:
1. Click Edit-System parameters and select the PLC tab.
2. Select PLC Type as Modbus RTU TCP/IP.
3. Select PLC I/F port as Ethernet.
4. For the Multiple OIT box, select Enable.
5. Select Slave from the Multiple OIT box.
6. Select Ethernet for the Connect I/F.
7. Select a unique station number in the OIT station no. box for each slave OIT, and click OK.

Shar ing Data Be tween the Mas ter OIT, Slave OIT and PLC

Mas ter OIT to a PLC
The master OIT will be programmed just as if it were the only OIT connected to the PLC.
Slave OIT to a Mas ter OIT
Any local word registers (LW) or local bits (LB) located in the master OIT can be accessed (read) and written to
(write) by the slave OITs. Do this by using the "Ms_LW" and "Ms_LB" memory registers. For example, if the
master OIT is storing data in LW10, the slave OIT can access that data by using a device type: Ms_LW and device
address: 10. Multiple OIT is set to Master. Connect I/F is set to Ethernet.
Slave OIT to the PLC
The slave OITs may access data in the PLC in two ways:
1. It may write to the local words/bits in the master OIT (via Ms_LW and Ms_LB registers), and
those values may be transferred to the PLC by setting up a data transfer object in the master
OIT program. Note: If the master and the slave OITs are accessing the same areas of memory
in the PLC, this method is more efficient because the time required to get information from
the PLC is reduced.
2. It may read/write directly to the PLC addresses (as though it were the only OIT connected to
the PLC). Note: This method may result in inconsistent Master/Slave communications.
Maple Systems recommends using method #1.
Man ag ing Com mu ni ca tion Fail ures
When communicating with multiple devices over a network, it is possible that one or more of the devices may fail
without affecting other devices on the network. When this happens, plant personnel may need to be notified of the
failure, while still maintaining communications with the rest of the network.
Communications failures to any node can be managed by the OIT. A series of local bits monitor and control
communications failures on both the main and auxiliary communications ports.
When a communications failure is detected on a particular PLC node address, the corresponding local bit will be
turned off, and communication to that node address is suspended. To restart communications to that node, the bit
must be turned back on.
Bits
LB9100-9227
LB9228-9355
PLC Node
Main port nodes 0-127
Aux port nodes 0-127
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