Sierra Instruction Manual InnovaSonic
®
203 Economical
48
9.
Appendix1-Serial Interface Network Use and
Communications Protocol
9.1
Overview
The flow meter comes standard with a RS-485 multi-drop communication port. An option RS-232 communication
connection is available as a special. RS-232 can be used for point to point (one master one slave 203) communication
only with wire runs of 50 feet or less. The RS-485 can be used to communicate over 1,000 meters baud rate dependent
with several 203 slaves on one wire pair. This could be up to 30, 203s on one RS-485 segment, and 127 on a whole
RS-485 network.
When the RS-485 communication method is used to implement a monitoring system network, the address
identification code (in menu M46) of the flow meter is used to set the Network ID in the 203 slave.
When using digital commutations the analog current loop and OCT output of flow meter can be free to be used to
control the opening of a control valve. The relay output can be used to power-on/off other equipment. The analog
input of the system can be used to input signals such as pressure and temperature. These analog values can be read
using the Modbus RTU protocol to be used by customer software.
RS-232 (<50 ft.) or RS-485 (up to 4,000 ft.) can be directly used for data transmission link for a short distance.
Current loop, radio transmission and modems can be used in medium or very long distance transmission.
When the flow meter is used in a network environment, various operations can be performed at the host device, except
for programming of the address identification code, which needs to be done at the flow meter keyboard. The
command answer mode is used in data transmission, i.e. the host device issues commands and the flow meter answers
correspondingly (polling communications).
ATTENTION
RS-232 and RS-485 serial communications cannot be used at the same time.
9.2
Serial Port Pin Definitions
Flow meter RS-232:
TXD receive
RXD send
GND
PC 9 pin Com Port:
PIN 1 empty
PIN 2 RXD receive
PIN 3 TXD send
PIN 4 ground
