Introduction. Endres+Hauser Tankvision NXA820, NXA821, NXA822

The "System" menu Tankvision

12.11.7 Entis Host Protocol

Introduction

Introduction Entis+ host protocol

Enraf provides for their tank systems Entis+ the Entis Host protocol to connect to host system. The physical layer is normally the RS232 interface, but in our case also RS484 is possible.

Protocol structure

The protocol is designed as ASCII-Protocol. The transmission flow is quite simple:

The Host sends a request and the "Entis system" must answer. There is no special handshake between both. The telegram is starting with STX (Hex02) followed by data. The data and additional information are separated by a separator sign. The telegram is ending with an

ETX (Hex03). A Block control character is added, either before or after the ETX. The structure is as following for the Host request:

[STX]<request code no.><name><command, request><data><[ETX][LRC], e.g for an Entity request code 1. [STX]1TNK-01[ETX][LRC]

The answer telegram is depending on the packet type requested:

[STX]<execution code>/<name>/<data>/[ETX][LRC], e.g. for an Entity request code 1.

[STXJ0/TNK-01/07-28-92/11:58:24/_269/-1-/+/_21.0/-/NORMAL/B/_727.40/

_32.65/_27.62/_20.09[ETX][LRC].

The execution code indicates the status of the reply package:

• "0" request executed successfully

• "1" request NOT executed successfully

• "2" the last entity in a successfull group request

Supported codes by the NXA822 are:

1. The entity request, code 1, which is used to get the data of one tank.

2. The group request, code 2, to get the data of all tanks a defined group.

3. The download command, code 3, to write a density value to a tank on the NXA820.

174 Endress+Hauser