I) V24/RS232/485-Interface - Basics

Protocol settings of a serial interface between a test bench control computer

and peripheral analyzers on exhaust test benches

1. Introduction

The serial interface is made for slow point to point connections (f 10 Hz). The communication between the test bench control computer (TBCC) and the peripheral analyzers works according to the master slave principle. That means that the peripheral analyzers will only answer with a response telegram to the command telegram of the TBCC. They will not send an own message.

You can distinguish two cases:

(1)Analyzers in a function unit (system)

Some analyzers are combined to a logical unit. They are connected to the TBCC via an front-end computer. In that case the communication will not take place directly between the TBCC and the analyzers, but between the TBCC and the front-end computer. Each analyzer or the whole system unit will be identified by a defined channel number:

K0 is the channel number for the whole defined system. ("Assembling command resp. assembling report")

Kn (n=1, nmax) is the channel number for each analyzer. KV is the channel number for the front-end computer.

(2)Single analyzers

Each analyzer is connected directly to the TBCC. In that case the identification of each analyzer will be done by the hardware connections and not by a software control. That is why the two channel number bytes (Kn) could be deleted. But in spite of that the channel number is generally 0 (K0) to get a uniform protocol.

The data transfer will only be done by ASCII code to get an easy handling of the protocol with a terminal for simulation of the TBCC, the system unit and the analyzers. Therefore, no parity check will be done as data saving.

90003752(1) [AK-Commands] 10/98

AK

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