To Next Page

To Previous Page

Touchpoint 4 Serial Communication Protocol Issue 1 09/07

Communication Port

Access to the Touchpoint4 protocol is through the terminal block on the common

module of Touchpoint4 gas detector controller. This port is designed for bidirectional

communications between the Touchpoint4 instrument and your master.

Signals present at the port conform to RS-485 specifications. The pin-out specifications

are described in the chapter

connectors pin-out.

Address Setting Procedure

After the networking cabling has been connected to the slave, the slave must be

configured to communicate. Baud rate and address are selectable. Configuration is

performed with the following sequence:

1. Access the menu system and select the

RS485 communication link

settings menu option. Press UP/DOWN, the icon flashes.

 2. PressOK,thecontroller’scurrentaddressisdisplayed.

3. Use UP/DOWN to change the address (between 1 and 16 available).

4. Press OK to accept the change.

The display changes to display the current baud rate.

 5. UseUP/DOWNtochangethebaudrate(1200,2400,4800,9600,

  19200available).

6. Press OK to accept the change.

Please refer to the Technical Manual for more details.

Protocol Specics

Theprotocolhasbeendesignedforflexibilityandefficiency.Thisbyte-wiseprotocol

communicates information by transferring bytes of data back and forth between master

and slave. A group of bytes for each communication is called a packet.

The master and slave(s) transfer information via data packets. These packets will always

contain bytes to start communication, an address, a length, a command, one or more

data and a checksum.

Additional optional variable-length data bytes or optional parameters can also be sent

or received. This section is a brief overview of the protocol specifics.

Packet Length

Just as all words are not the same length (number of letters), packets may also vary in

length. In this protocol, the length of command and data field is put before command

fieldinthepacket.Yourdatacontaining"0x42,0x41,0x44"willthenbecome“0x03,

0x42,0x41,0x44”.

Honeywell Touchpoint 4 User Manual

Questions and Answers: