Configuring Passthrough Mode - Emerson Micro Motion 3711 Configuration And Use Manual

Setting Up Communications
Table 4-5 Comm Port – RBX panel continued
Parameter Description
RBX Alarm Index Displays any alarms currently being reported through the RBX
feature.
RBX Status Indicates the status of RBX message:
• Active: An RBX alarm is being processed.
• Inactive: No RBX alarm is being processed.
RBX Ack Timeout Enter the number of seconds that the Model 3711 will wait for
the host to respond to an RBX message with an ACK
(acknowledgment) message.
4.7

Configuring passthrough mode

Passthrough mode allows the Model 3711 to receive a message from a host via one port (the receiving
port) and automatically retransmit the message to other devices on the network through another port
(the sending port).
For example, a Model 3711 could be set up to receive host communications through the LOI. If
passthrough from LOI to COMM 2 is configured (i.e., the LOI is the receiving port and COMM 2 is
the sending port):
• All messages received through the LOI that are addressed specifically to the passthrough
device will be processed locally, and will not be retransmitted.
• All other messages received through the LOI will be automatically retransmitted over
COMM 2.
Any device accessible via the sending port can receive the retransmitted message, depending on the
protocol used, the device group and device address specified in the message, etc.:
• If ROC protcol is used for the message, only devices in the same device group as the
Model 3711 will receive the retransmitted message.
• If Modbus protocol is used for the message, all other devices on the network will receive the
retransmitted message.
Note: Because COMM 1 is dedicated to sensor communications, only the LOI and COMM 2 can be
used when configuring passthrough mode.
Note: If COMM 2 is used as a dial-up modem, and you want to configure it for passthrough, it must
be defined as the receiving port. It cannot act as the sending port.
To set up passthrough mode:
1. Ensure that the necessary wiring is in place between the Model 3711's sending port and all
receiving devices.
2. If ROC protocol will be used, ensure that all receiving devices are members of the same device
group (see Section 3.4).
3. At the Model 3711 which is directly connected to the host, specify the pair of ports that will be
used for passthrough mode. The Flags window, Advanced panel, is used for this configuration
(see Figure 4-6). To access the Flags window, click
34
Comments
If no ACK is received within the
specified time, the Model 3711
continues with retry and attempt
processing.
.
Device > Flags
®
Micro Motion Model 3711 Gas Flow Computers