Short description protocol ES40 - Krohne

Short description protocol ES40 

Version 1.4 

1. Intended use. 

The ES40 communication protocol is intended for data exchange between 

Cargomaster and other computer units. Its main property is ease of implementation 

and debugging, which will lower the cost of development for new users. 

Transport media is RS 232C, resulting in a relatively slow operation. The advantage, 

on the other hand, is low cost and standardisation among systems. 

Typical application of ES40 is data exchange from: 

- External level gauging systems to Cargomaster, for example from purged air 

systems. 

- Cargomaster to shipboard computer systems. 

- Cargomaster to separate loading computer. 

- Ballastmaster to shipboard computer systems 

2. Data transmission, transmit and receive 

The ES40 is an ASCII protocol, which in case of communication failure makes it easy 

to isolate the system causing problems. (This is done by simply hooking up a terminal 

on the serial line, and watching the data flow.) 

Tank data 

Data is transferred sequentially, one line pr tank, with a configurable delay between 

each line. 

The tank number (Range 1 to 499) is always the first data item in each line, after the 

start byte(s) and separator. Following the tank number are the selected values to be 

transmitted. The engineering units and number of decimals for all available values are 

described in chapter 3. Each line (packet) of data is terminated by an optional 

checksum and a mandatory [CR][LF] 

Note: All tanks in one system will have the same data types transmitted. This means 

that if for example temperature is to be transmitted for cargo tanks, the temperature 

(or -9999 if invalid) need also be sent for all other tanks. However, data transmitted 

from a system may differ from data received, making it possible for example to send 

ullage, volume, density and temperature for selected tanks, while receiving only 

innage and volume. 

The type of data transferred pr. tank may vary between applications, and is agreed 

between the parties before establishing the link. 

Draft 

Drafts are assigned tank numbers if such data is to be transmitted. This means that 

for each draft, a line containing the same data items as the tanks will be transmitted. 

Irrelevant data as temperature or other tank data must be ignored by the receiver. 

Please note that draft may not be transmitted as a data item in other tank packets. 

Doc no. 60809001 Rev 1.4 empress\fou\doc\approved documnets\60809001.doc Page 1 of 6

Error indication 

Invalid data is indicated by sending -9999 in the data field, for example after failure of 

a transducer or lack of user input data. 

Cargo line pressure 

Tank numbers above 900 are used to indicate load-line pressure data rather than tank 

data. 900 is added to the line pressure number before transmission, and the only data 

transmitted is pressure and, optionally, alarm status. The format of the data packets 

containing cargo line pressure will vary from the format of the tank data packets. 

System data 

As an option at the beginning of each transmit cycle, system data (trim, list, and 

atmospheric pressure) may be transferred on a separate line. The format of this data 

packet is fixed, and is indicated by setting zero in the tank no field. 

Data transmitted will be: 

[start][sep]0[sep]Trim[sep]List[sep]Atmospheric pressure. 

The start byte(s), separator and optional check sum will be used as globally configured 

for the system. 

The example in chapter 5 includes the system packet. 

Start byte(s). 

The start-byte is configurable. It is strongly recommended to use a printable character 

in the decimal ASCII range 33 to 42, or ASCII 64. The default is ASCII 64 (@). 

The number of start bytes is also configurable to allow for synchronisation bytes, 

please pay attention to the checksum description below when using multiple start 

bytes. 

Separator 

One separator is used between data items. The byte may be configured using the 

same guidelines as for the start byte, but the ASCII value of the start and separator 

byte may not take the same value. The default separator is space (ASCII 32), which is 

strongly recommended. 

The separator byte is inserted between all data items, also between the start byte and 

the tank no, but not before the [CR][LF] packet terminator. 

Stop bytes. 

To terminate each data packet, [CR][LF] is always used. 

Checksum. 

The use of checksum is optional. If used, the checksum is the eight bit sum of all 

preceding characters on the same line. Regardless of the number of start bytes used, 

only one start byte is to be used for checksum calculation. The [CR][LF] packet 

terminator is succeeding the checksum, and is therefore not included in the 

calculation. 

The decimal value of the checksum is transmitted as three ASCII characters in order 

to avoid non-printable characters in the telegram. 

The examples in chapter 5 include calculated checksum. 


3. Units. 

Units for data transfer are: 

Temperature: 0C with one decimal (Tank average or any sensor temp) 

Draft: Meters with three decimals (Specify as level) 

Innage (flot.lev): Meters with three decimals (Level in flotation centre) 

Innage (level): Meters with three decimals (Level at manual ref. point) 

Ullage: Meters with three decimals (Ullage at manual ullage hatch) 

Inert gas pressure: mmWg with no decimals 

Weight: Metric ton with three decimals. 

Volume: m3 with three decimals 

Volume % of full: % with two decimals 

Ref. temperature: 0C with one decimal (Ref. temperature 1 or 2 from operator) 

Density: Density in air with five decimals, t/m3 (Actual dens., measured dens. or any operator input dens.) 

Density coefficient: Density change pr. 0C with five decimals, t/(m3 0C) Loadrate: m3 /h with one decimal 

Tank name: String of max. 8 characters 

Pressure: mmWg with no decimals for any tank pressure sensor. 

Tank type: 

First byte: 

Two consecutive bytes (No separator between bytes): 

Bit 7 - 0 

Bit 6 - 1 

Bit 5 - 1 = Variable solid (Load calculator only) 

Bit 4 - 1 = Constant solid (Load calculator only) 

Bit 3 - 1 = Misc. tank 

Bit 2 - 1 = Fuel tank 

Bit 1 - 1 = Ballast tank 

Bit 0 - 1 = CARGO tank 

Second byte: 

Bit 7 - 0 

Bit 6 - 1 

Bit 5 - Density display type *) 



Bit 2 - 1 = Online tank / 0 = Offline tank 

Bit 1 - 1 = Temp. tank 

Bit 0 - 1 = Draft tank 

*) Density display type: 

0 = Linear (Density @15 0 C and coefficient) 

1 = API CRUDE 

2 = API PRODUCT 

3 = API LUB OIL 

4 = API BALLAST 

5 = ASTM54b 

6 = Future use 

7 = Future use 


Alarm status: Three consecutive bytes (No separator between bytes): 

First byte: 

Bit 7 - 0 

Bit 6 - 1 

Bit 5 - Future use 

Bit 4 - 1 = Horn on (Set to 1 if horn is on) 

Bit 3 - 1 = Sensor disabled 

Bit 2 - 1 = Hardware error on tank/line measurement 

Bit 1 - 1 = Alarm active (Active =1, Acknowledged=0) 

Bit 0 - 1 = Any alarm (active or acknowledged) in tank/line-pressure 

Second byte: 

Bit 7 - 0 

Bit 6 - 1 

Bit 5 - 1 = High High level 

Bit 4 - 1 = High level 

Bit 3 - 1 = Low level 

Bit 2 - 1 = Low Low level 

Bit 1 - 1 = High inert pressure (High pressure for line pressure) 

Bit 0 - 1 = Low inert pressure (Low pressure for line pressure) 

Third byte: 

Bit 7 - 0 

Bit 6 - 1 




Bit 2 - 1 = High temperature 

Bit 1 - 1 = Low temperature 

Bit 0 - 1 = Density difference (Deviation manual/measured density) 

Line pressure: mmWg with no decimals 

Atmospheric press.: mmWg with no decimals 

Trim: Degrees (360) with five decimals, Negative aft 

List: Degrees (360) with five decimals, Negative port 

Note: 

All above values are valid for output from Cargomaster. The following values are valid for 

input, taking the same units and number of decimals as for output: 

Ullage Volume Vol% Temperature (Average only) 

Inert press Density (As output) Density expansion Atmospheric pressure 

Level (Flot.) Dens. ref. temps. Trim List 

Level (Ref. Pt.) 


4. Handshaking, data format and speed. 

The protocol uses no handshaking or control flow signals. Neither is there a need to 

request data, as each sender transmits the agreed data sequentially in an endless 

loop. 

This means that an ASCII terminal (or a PC with terminal emulator) can be hooked up 

on the line to check the data flow from each node in the system. (RX, TX and ground 

are the only lines connected.) 

Hardware data format: 

Speed: 300 to 19200 Baud. Default 9600 Baud 

Stop bits: 1 or 2. Default 1 

Start bits: 1 

Parity: Odd/even/none Default none 

Packet delay. 

The delay between each line(packet) of data is configurable. A typical system will 

delay 0.3 seconds between the start of each line. 

5. Example. 

A typical sequence (Start byte=$, Separator=space, Checksum included) to transmit: 

System data 

Innage, ullage, volume, volume%, inert pressure, 4 temperatures for tank 1 to 5 

Line pressure points 1 to 4 

$ 0 -0.06356 0.08881 9200 181 

$ 1 0.000 14.574 0.000 0.00 6 25.4 25.5 25.4 25.4 221 

$ 2 0.000 14.582 0.000 0.00 -14 25.2 25.3 25.2 25.2 049 

$ 3 0.000 14.566 0.000 0.00 9 -9999.0 -9999.0 -9999.0 25.2 210 

$ 4 0.000 14.570 0.000 0.00 3 -9999.0 -9999.0 -9999.0 25.2 200 

$ 5 0.000 14.560 0.000 0.00 -10 -9999.0 -9999.0 -9999.0 25.2 035 

$ 901 6617 242 

$ 902 7189 248 

$ 903 7786 252 

$ 904 9112 238 

Detail of the first line of the above telegram: 

$ 0 - 0 . 0 6 3 5 6 0 . 0 8 8 8 1 9 2 0 0 1 8 1 CR LF 

The above cycle will be transmitted in an endless loop. 


6. Options 

As implemented by Scana Skarpenord, the above protocol may be substituted by the 

Simrad "Standard AVM" protocol. The implementation will generate one line (packet) 

of data pr tank, and treats the tank number as an analogue value. In all other aspects 

(i.e error indication, separators, checksum etc.) the Simrad AVM protocol description 

(Doc.no.sa13304) is followed. 

Langesund, Sep 10. 1999 

H.Hogner

Short description protocol ES40 - Krohne

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?