TSI Instruments PRESSURA RPC30 User Manual

89
Appendix B
Network Communications
Network communications are available on the PresSura room controllers. The PresSura room
controllers can communicate with a building management system through Modbus
®
, LonWorks
®
or BACnet
®
MS/TP protocols. Please refer to the appropriate section below for more detailed
information.
Modbus
®
Communications
Modbus
®
communications are installed in the PresSura room controllers. This document provides
the technical information needed to communicate between the host DDC system and the
PresSura room controllers. This document assumes the programmer is familiar with Modbus
®
protocol. Further technical assistance is available from TSI if your question is related to TSI
interfacing to a DDC system. If you need further information regarding Modbus
®
programming in
general, please contact:
Modicon Incorporated (a division of Schneider-Electric)
One High Street
North Andover, MA 01845
Phone (800) 468-5342
The Modbus
®
protocol utilizes the RTU format for data transfer and Error Checking. Check the
Modicon Modbus
®
Protocol Reference Guide (PI-Mbus-300) for more information on CRC
generation and message structures.
The messages are sent at 9600 baud with 1 start bit, 8 data bits, and 2 stop bits. Do not use the
parity bit. The system is set up as a master slave network. The TSI units act as slaves and
respond to messages when their correct address is polled.
Blocks of data can be read from each device. Using a block format will speed up the time for the
data transfer. The size of the blocks is limited to 255 bytes. This means the maximum message
length that can be transferred is 255 bytes. The typical response time of the device is around 0.05
seconds with a maximum of 0.1 seconds.
Unique to TSI
The list of variable addresses shown below skips some numbers in the sequence due to internal
PresSura room controller functions. This information is not useful to the DDC system and is
therefore deleted. Skipping numbers in the sequence will not cause any communication
problems. If a variable is not used by the particular PresSura room controllers, it will be reported
with a value of -1.
All variables are outputted in English units: ft/min, and cfm. If the DDC system is to display
different units, the DDC system needs to make the conversion.
Modbus is a registered trademark of Modicon, Inc.

TSI Instruments PRESSURA RPC30 Specifications

General

Brand	TSI Instruments
Model	PRESSURA RPC30
Category	Controller
Language	English