Invalid Port Configuration Combinations; Rtu Slave/Snp Slave Operation With Programmer Attached - GE VersaMax PLC User Manual

Serial I/O / SNP / RTU Protocols
For public disclosure

12.2.3 Invalid Port Configuration Combinations

The configurations of both ports must be compatible. One port must be available for PLC
programmer connection.
The CPU rejects the following combinations:
Port 1
Disabled
Disabled
Serial I/O
(CPU Run/Stop switch disabled)
Serial I/O
(CPU Run/Stop switch disabled)
Station Manager
Station Manager
12.2.4 RTU Slave/SNP Slave Operation With
Programmer Attached
A programmer (an SNP/SNPX device) can be attached to port 1 or port 2 while RTU
Slave mode is active on the port. For multi-drop connections, the CPU must have been
configured to use an appropriate PLC ID. Note that for a multi-drop SNP connection with
the port currently configured for RTU, the SNP ID associated with the CPU settings must
match the multi-drop ID.
The programmer must use the same serial communications parameters (baud rate, parity,
stop bits, etc.) as the currently-active RTU Slave protocol for it to be recognized.
When the CPU recognizes the programmer, the CPU removes the RTU Slave protocol
from the port and installs SNP Slave as the currently-active protocol. The SNP ID,
modem turnaround time, and default idle time for this new SNP Slave session are
obtained from the configured CPU settings, not the port 1 or port 2 configurations.
Connection should be established within 12 seconds. When the programmer connection
has been enabled, normal programmer communications can take place. (Failure of the
programmer to establish communications within 12 seconds is treated as a Loss of
Programmer Communications).
The programmer may send a new protocol via configuration or a Serial Port Setup
COMMREQ. (COMMREQs not supported by SNP Slave protocol are rejected). If a new
protocol is received, it will not take effect until the programmer is disconnected.
After the programmer is removed, there is a slight delay (equal to the configured SNP T3'
timeout) before the CPU recognizes its absence. During this time, no messages are
processed on the port. The CPU detects removal of the programmer as an SNP Slave
protocol timeout. Therefore, it is important to be careful when disabling timeouts used by
the SNP Slave protocol.
When the CPU recognizes the disconnect, it reinstalls RTU Slave protocol unless a new
protocol has been received. In that case, the CPU installs the new protocol instead.
Port 2
Disabled
Serial I/O
(CPU Run/Stop switch disabled)
Disabled
Serial I/O
(CPU Run/Stop switch disabled)
Disabled
Serial I/O
(CPU Run/Stop switch disabled)
GFK-1503E User Manual 229