Timing; Sending Another Commreq To The Same Port; Invalid Port Configuration Combinations; Commreq Command Block Parameter Values - Emerson PACSystems RX3i User Manual

PACSystems™ RX3i and RSTi-EP CPU Reference Manual
GFK-2222AK

Figure 19: COMMREQ Example

6.1.2

Timing

If a port configuration COMMREQ is sent to a serial port that currently has an SNP master
(for example, the programmer) connected to it, the COMMREQ function returns an error
code to the COMMREQ status word.
6.1.3

Sending Another COMMREQ to the Same Port

After sending a COMMREQ to configure a serial port, the application program should
monitor the COMMREQ status word to determine when it can begin sending protocol
specific COMMREQs to that port. It is recommended that the application clear the
COMMREQ status word prior to issuing the configuration change. The status word will be
set to a nonzero value when the request has been processed.
6.1.4

Invalid Port Configuration Combinations

The PAC Machine Edition programming software safeguards against the download of
some hardware configurations that would prevent the programmer from communicating
serially with the CPU. In a system that does not have an embedded Ethernet module, if a
rack-based Ethernet is not present, a serial connection is required for programmer
communications.
For CPE302/CPE305/CPE310 CPUs, which have an embedded Ethernet port that, when
configured, is available for programmer communications, the safeguards on serial port
configurations are still enforced.
For CPE400 and CPL410, which only support the Serial I/O protocol, the only valid
operation is to enter Serial I/O as the Protocol Selector (refer to Section 6.1.5).
6.1.5

COMMREQ Command Block Parameter Values

The following table lists common parameter values that are used within the COMMREQ
command blocks for configuring a serial port. All values are in decimal.
Serial I/O, SNP & RTU Protocols
Section 6
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