User Guide Instruction Manual

DeviceMaster UP Modbus/TCP User Guide: 2000447 Rev. I Chapter 2. Programming Interface - 61
Sequence Number Messages
2.4.5. Sequence Number Messages
PLC-5/SLC typed read and typed write messages can read and modify both receive and transmit produced
data sequence numbers. These are the same sequence numbers returned to the PLC in the Receive Data
Message and sent to the DeviceMaster UP in the Transmit Data message. Access to these sequence numbers
are provided primarily for initialization purposes at the start of the PLC program when you may want to
initialize the sequence numbers on the PLC, DeviceMaster UP or both.
PLC-5/SLC typed read and write messages can also read and modify the consumed receive sequence
number(s). The consumed receive sequence number(s) are used in the Write-to-File-Synced communication
method.
2.4.6. Retrieve Statistics Message
The data returned from the Retrieve Statistics message is identical to the data returned for the Serial Port
Statistics Object. The Retrieve Statistics message formats the data into 32-bit integers and returns data in an
array of s just like all data sent to a PLC-5 or SLC PLC. The first contains the least significant word and the
second contains the most significant word.
The following table displays the format of the Retrieve Statistics message.
The Retrieve Statistics messages have the following characteristics.
Index Name Data Type Data Value(s) Access Rule
1 Receive Byte Count UDINT 0=default Read only
2 Receive Packet Count UDINT 0=default Read only
3 Transmit Byte Count UDINT 0=default Read only
4 Transmit Packet Count UDINT 0=default Read only
5 Dropped Packet to PLC Count UDINT 0=default Read only
6 Parity Error Count UDINT 0=default Read only
7 Framing Error Count UDINT 0=default Read only
8 Overrun Error Count UDINT 0=default Read only
9
Received Consumed Sequence Error
Count
UDINT 0=default Read only
10
Duplicate Transmit Sequence Number
errors
UDINT 0=default Read only
11
Unexpected Transmit Sequence
Number errors
UDINT 0=default Read only
12 Dropped Packet to Application Count UDINT 0=default Get
Retrieve Statistics Message Description
Receive Byte Count This attribute counts the number of bytes received on the serial port.
Receive Packet Count This attribute counts the number of packets received on the serial port.
Transmit Byte Count This attribute counts the number of bytes transmitted on the serial port.
Transmit Packet Count This attribute counts the number of packets transmitted on the serial port.
Dropped Packet to PLC Count
This attribute counts the number of dropped receive packets on the serial
port intended for the PLC due to:
• No STX byte(s) found
• No ETX byte(s) found
• Time-outs
• Too large of packet
• Receive buffer queue overflows