Quest Controls BACnet T-Stat Instrukcja Obsługi Pobierz pdf (Strona 224)

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224 • Fieldbus Communication

MODBUS Functions

WAGO-I/O-SYSTEM 750

BACnet/IP Controller

4.3.3.7 Function Code FC11 (Get comm event counter)

This function returns a status word and an event counter from the slave de-

vice’s communication event counter. By reading the current count before and

after a series of messages, a master can determine whether the messages were

handled normally by the slave.

Following each successful new processing, the counter counts up. This count-

ing process is not performed in the case of exception replies, poll commands

or counter inquiries.

Request

Byte Field name Example

Byte 0, 1 Transaction identifier 0x0000

Byte 2, 3 protocol identifier 0x0000

Byte 4, 5 length field 0x0002

Byte 6 unit identifier 0x01 not used

Byte 7 MODBUS function code 0x0B

Response

The reply contains a 2-byte status word and a 2-byte event counter. The status

word only contains zeroes.

Byte Field name Example

.....

Byte 7 MODBUS function code 0x0B

Byte 8, 9 Status 0x0000

Byte 10, 11 Event Count 0x0003

The event counter shows that 3 (0x0003) events were counted.

Exception

Byte Field name Example

.....

Byte 7 MODBUS function code 0x85

Byte 8 Exception code 0x01 or 0x02

1 2 ... 219 220 221 222 223 224 225 226 227 228 229 ... 359 360

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