Transmit data message – Comtrol UP DeviceMaster User Guide User Manual
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60 - Chapter 2. Programming Interface
DeviceMaster UP Modbus/TCP User Guide: 2000447 Rev. I
Transmit Data Message
2.4.4. Transmit Data Message
The Transmit Data message format is similar to the format used in the Serial Port Data Transfer Object.
However, the data is in 16-bit integer format instead of byte format. The 16-bit integer format is required
when connecting to PLC-5 and SLC PLCs.
The following table displays the format of the Transmit Data message.
Transmit messages have the following characteristics:
•
It transfers all data in UINTs.
•
The data length field indicates the number of valid bytes contained in the message.
•
The actual length of a message received from the PLC may contain extra, unused data.
•
It ignores all unused bytes in a message.
•
The default order of the bytes is Least Significant Byte First. However, you can select the (PLC-5/SLC) Tx
MS Byte First option in the web page to transmit bytes by Most Significant Byte First. For more
information, see (PLC-5/SLC) Tx MS Byte First under
3.3.3. Serial Packet Identification
•
A Get returns the last successfully transmitted serial/socket packet.
Name
Data Type
Data Value(s)
Access Rule
Transmit (PLC to DeviceMaster UP) message data
Structure of:
Produced data sequence number
Data length (in bytes)
Data array
UINT
UINT
Array of UINT
0-65535 (FFFF hex)
1-202 (
SLC
) 1-222 (
PLC-5
)
0-65535
Read/Write