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100 Micro Motion
®
Series 3000 MVD Transmitters and Controllers
Configuring Digital Communications
Polling address
Two polling addresses are stored on the Series 3000 device: a Modbus polling address and a HART
polling address.
• The Modbus polling address can be configured only in the RS-485 menu, and is used for all
Modbus communications.
• The HART polling address can be configured either in the RS-485 menu (if HART protocol is
specified) or in the Bell 202 menu. Because only one value can be stored, if Polling Address is
set in both menus, the most recent address will be used for HART communication over both
the RS-485 terminals and the primary mA/HART terminals.
Communicating with a remote device
After RS-485 communications have been set up (both wiring and configuration), there are two
communication methods available:
• Service port mode
• RS-485 mode
Note: Service port connections use standard settings and do not require transmitter configuration.
Therefore, they are easy and convenient. However, the standard settings and the address may not be
compatible with your network, and the service port cannot be used when the custody transfer
application is installed and the transmitter is secured.
Immediately after the Series 3000 device is powered up, the RS-485 terminals are available in service
port mode for 10 seconds. To connect during this period, configure your remote device as described in
Table 13-2. If a service port connection is made, the terminals will remain in service port mode.
Table 13-1 HART, Modbus RTU, and Modbus ASCII parameters
Variable Default Description
Baud rate 9600 baud Select the baud rate to be used with the remote device.
Parity Odd Select None, Odd, or Even as required by the remote device.
Data bits 8 bits This parameter is read-only:
• HART and Modbus RTU – 8
• Modbus ASCII – 7
Stop bits 1 bit Enter 1 or 2 stop bits as required by the remote device. If HART is the
configured protocol, Stop bits must be set to 1.
Polling address 0 (HART)
1 (Modbus)
Enter the polling address to be assigned to the Series 3000 device.
• If Modbus/RS-485 protocol is configured, enter a Modbus polling address.
Valid Modbus polling addresses are in the following ranges: 1–15, 32–47,
64–79, 96–110.
• If HART/RS-485 protocol is configured, enter a HART polling address. See the
discussion in the following section. Valid HART polling addresses are in the
range 0–15. If the HART polling address is set to any value other than 0, the
primary mA output is fixed at 4 mA, and will not report process variable data or
fault conditions.
Byte order 3–4–1–2 (Modbus RTU or Modbus ASCII only) Specifies the floating point byte order for
Modbus communications. Select one of the following:
• 1–2–3–4
• 3–4–1–2
• 2–1–4–3
• 4–3–2–1