Phoenix Contact 2702772, User Manual

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MicroLogix, SLC, and PLC-5 interface
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6.5 Transmit data message
When connecting to MicroLogix, PLC-5, and SLC PLCs, transmit data messages are
formatted in 16-bit integer format.
6.5.1 Transmit message characteristics
Transmit messages return 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.
All unused bytes in a message are ignored.
The default order of the bytes is least significant byte first.
A “Get” command returns the last successfully transmitted serial/socket packet.
6.6 Sequence number messages
PLC-5 and 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 GW EIP/ASCII... in the
“Transmit Data” message. Access to these sequence numbers are provided primarily for
initialization purposes at the start of the PLC program to initialize the sequence numbers on
the PLC, GW EIP/ASCII..., or both.
Table 6-5 Transmit data message format
Name Data type Data value Access rule
Structure of:
Product data sequence
number
UINT 0 - 65535 (FFFF
hex
) Read/Write
Data length (bytes) UINT 1 - 202 (SLC), 1 - 222
PLC-5)
Read/Write
Data array Array of UINT 0 - 65535 Read/Write