Momentum Modbus Plus 170 PNT Series Guia do Utilizador descarregar pdf (Página 162)

Using the Ethernet Port

162

870USE10110 July 2004

Transmission

Errors

Transmission errors table

Words Description

Words 26, 27

Transmit Buffer

Errors

Increments when the M1 is unable to transmit an Ethernet response

frame because all frame buffers are in use. For example, the M1 has 16

ping reply buffers. If all 16 ping buffers contain ping replies, ready to be

transmitted, but this station’s transmission is delayed because of

collisions and back-off, and one more ping request is received, then the

new ping request is discarded and the counter is incremented. This error

can occur for ping, ARP, and connection attempt to server path. Although

this error is theoretically possible, it is not usually encountered.

Words 28, 29 Silo

Underflow

This field counts M1 TCP/IP retries. All M1 clients and server use the

TCP/IP protocol which implements sequence numbers and time-outs.

Whenever TCP/IP data is pushed from the M1, a subsequent

acknowledgement of receipt of M1 data must be received within the

timeout period, or else the M1 issues a retry. Retries may be the result of

any of the following conditions:

The original M1 data frame was garbled, corrupted, and lost

The target TCP/IP stack is operating more slowly than the M1 retry

rate

For Modbus 502 servers, the M1 initiates retries after (1, 1, 2, 2, 4, 8)

seconds.

For Modbus 502 clients, the M1 retry rate is the larger of:

1/4 the health timeout for Ethernet I/O Scanner data (see p. 290) or

4 times the previous measured TCP/IP round trip time for I/O

scanner MSTR block.

Words 30, 31

Late Collision

Increments when the transmit frame process is aborted because of late

collision detected after the first 64 bytes of the frame was transmitted

collision free. This error could possibly occur if the Ethernet cable is

intermittently connected and disconnected.

Words 32, 33,

Lost Carrier

Increments whenever the Ethernet cable, connected to the M1, is

disconnected from the hub. Also increments whenever the Ethernet

cable, connected to the hub, is disconnected from the M1.

Words 34,35 16

Collision Transmit

Failure

Transmit frame process was aborted after 16 consecutive collisions. The

frame was not successfully transmitted out onto Ethernet link. This error

should never occur.

1 2 ... 157 158 159 160 161 162 163 164 165 166 167 ... 375 376

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