Siemens 3964 protocol for MORSE

1. Introduction

This protocol is compatible with protocol Siemens 3964 used in equipment 
such as CP521 SI,CP523 SI,CP524 SI, CP525 SI produced by Siemens.

2.Data format

2.1. The physical layer

Protocol is normally used for asynchronous communication on a full duplex 
V.24 interface (RS232), using only data signals RXD, TXD, and ground (3-
wire communication).

2.2. The link layer
The link layer behaves according to the description of Siemens 3964 
protocol.

2.3. Network layer

When a programmer needs to send a datagram from some Siemens equipment over 
MORSE network, he must send the network layer header prior the data. 
Receiving process should strip this information from received buffer (there 
is address of the sender).

   | NETWORK HEADER | DATA | DLE | ETX |

Header structure (including example):

   |    T/8    | R/5 | N/3 | DST/16 | SRC/16 | L/16 |
     0000 1001  00000  111    5505     55FF    0002

Network layer data:

   | DATA |
     AAAA

   T   - Packet type
   R   - Reserved, must be zero
   N   - Network number (transferred over the network)
   DST - Destination Address
   SRC - Source Address
   L   - Length of data field
   DLE - 10
   ETX - 03

- Packet numbering is not compulsory. Only the lowest three bits from the 
number are transmitted. The entered number is transported to the 
destination address, and can serve to control the order of the delivered 
packets (the MORSE network does not guarantee a perfect order for packets).

- The maximum allowable length of data in the MORSE network layer is 1626 
bytes. Longer packets are not defined within the system. The  optimum 
packet size for MORSE system is 200-400 bytes.

- All 2-byte and 4-byte values are transferred in normal order. The highest 
byte is transmitted first, and then the lower ones (beware, as the Intel 
processor format is typically the opposite).


3. Communication example

>>
11:45:05.588|                 |690F5505 690F55FF|S01I    IN    2|89 7user 
AAAA
11:45:05.601 tx      1 | S01
02
11:45:05.610 rx;i    1 | S01
10
11:45:05.611 tx     12 | S01
0907 5505 55FF 0002 AAAA 1003
11:45:05.628 rx;i    1 | S01
10

The data AAAA came from the MORSE system to the SCC1 channel having set the 
Siemens 3964(R) protocol. The protocol sends the character 02 (=STX) to the 
link, obtains the character 10 (=DLE) from connected equipment Siemens. 
Then it sends the frame in Siemens format containing the data AAAA and the 
characters 1003 (=DLE ETX) on the end. The communication is terminated by 
receiving the character 10 (=DLE).


4. Protocol parameter settings

Configuration of the protocol using the  service terminal.

MARS-E parameters:
(a):1000ms  (r):5
(s):OFF  (p):LOW
(q)uit
>>

The link layer protocol is always configured using the protocol parameters:

(a) - ACK timeout - the time after transmitting a data frame in which the 
      transmitting station waits for an ACK frame. If the ACK does not 
      arrive, the frame is repeated.
(r) - Number of repeats - if the number of repeats is exhausted and the ACK 
      timeout expires, the network layer is informed that the packet is
      lost.
(s) - security - obsolete, set off
      substituted by Security parameter in the SIe menu 
(p) - priority - hihg/low - equipment communicating using the Siemens 
      3964(R) link layer must have a priority setting in case of collision. 
      Setting High - a packet is repeated after a collision 
      Setting Low  - is silent after a collision 
      Obviously, two pieces of equipment which are communicating together
      must be set so that one has High priority and the second has Low.
 

5. History

Former name of this protocol within MORSE equipment is MARS-E.