Rockwell Automation 1771-SDN DeviceNet Scanner Module Installation Instructions - Manual (Page 22)

Publication 1771-IN014B-EN-P - September 2001
22 DeviceNet Scanner Module Catalog Number 1771-SDN/C
To reduce block transfer time and increase system performance, use
only the words you need.
Use the RSNetWorx for DeviceNet software to map data from a
DeviceNet node into the scanner input table. Data from a DeviceNet
node can be split and put into as many as four different locations in
the scanner input table.
Module Status Register
In the Module Status Register (word 0, block 62), bits 0 through 5
indicate to the PLC-5 the current state of the scanner module. When
a Module Command Register command is sent to the scanner module,
the respective bits are set in the Module Status Register when the
command executes. Depending on network load, the scanner may
take several moments to detect network status changes. The bits latch
on in the “on” state until the command clears.
Bits 6 and 7 indicate that you should read the device failure table for
more specific information about which devices failed. Bits 8 and 9
indicate that you should read the device autoverify table to determine
which device has incorrect device keying or a misconfigured data size
in the scanner configuration tables. Use the DeviceNetManager
software to correct this error.
You can use bits 6 and 7 of the Module Status Register to enable
the scanner module’s Module Command Register to react to certain
conditions. An example reaction to a condition is to keep the
communication ports in the “idle” mode until the bits clear.
When the bits clear, this indicates that all devices on the networks are
operational. When the devices are operational, you can put the ports
in the “run” mode, so that output data goes to the devices.
If a device failure is detected, you can put the communication into the
“idle” mode, so that all devices would go into their idle state. You may
tie these inputs to the Module Command Register, so that you may use
them to adjust the operating mode of the scanner when devices fail or
go online at startup.
You can also modify your control logic to run differently to
compensate for the loss of communication with a certain node.
An alarm message to alert an operator of the problem is also possible.
The following table lists Module Status Register bit numbers and their
descriptions.