Overview

An M580 system can detect the existence of communication loss in the following ways:

  • a broken cable is detected by a CPU with Ethernet I/O scanner service and a BM•CRA312•0 (e)X80 EIO adapter module

  • a CPU with Ethernet I/O scanner service detects that a BM•CRA312•0 module has stopped communicating.

  • a BM•CRA312•0 module detects that a CPU with Ethernet I/O scanner service has stopped communicating

The time required by the system to detect each type of communication loss is described below.

Broken Cable Detection Time

A CPU and a BM•CRA312•0 module can detect a broken or detached cable within 5 ms of the occurrence.

NOTE: A network that includes up to 31 drops and a CPU with Ethernet I/O scanner service can recover communications within 50 ms from the time the cable break is detected.
NOTE: When a broken cable is connected to an RIO port and other cables on the ring are healthy, wait for the LINK LED (the status of the port) to appear before removing another cable in the system. If all links are broken simultaneously, the device goes into fallback state.

RIO Drop Loss Detection Time

A CPU with Ethernet I/O scanner service can detect and report the communication loss of a BM•CRA312•0 module within the time defined by the following formula:

Detection time = (xMultiplier * MAST period) + (CPU scan time), where:

  • MAST period / 2 = RPI for the MAST task

  • RPI = the input refresh rate from the BM•CRA312•0 module to the CPU

  • xMultiplier is a value in the range 4...64. The value xMultiplier is determined by the following table:

MAST period / 2 (ms)

xMultiplier

2

64

3...4

32

5...9

16

10...21

8

≥ 22

4

For RPI details, refer to the Connection Parameters topic in the Modicon M580 Remote I/O Modules Installation and Configuration Guide.

CPU with Ethernet I/O Scanner Service Loss Detection Time

A BM•CRA312•0 module in an RIO drop can detect the communication loss of a CPU with Ethernet I/O scanner service within the time defined by the following formula:

Detection time = (xMultiplier x MAST period / 2) + (CPU scan time), where:

  • MAST period / 2 = the output refresh rate from the CPU with Ethernet I/O scanner service to the BM•CRA312•0 module

  • xMultiplier is a value in the range 4...64. The value xMultiplier is determined by the following table:

RPI (ms)

xMultiplier

2

64

3...4

32

5...9

16

10...21

8

≥ 22

4