HERMOS LFM LP Reader - Page 72

Protocol description ASCII, SECS/HSMS
Customer manual
Version 1.2
LFM LP Reader 15.01.2019
Page 72 of 119
HERMOS AG
Gartenstrasse 19 Tel. +49(9279) 991-0
D-95490 Mistelgau Fax. +49(9279) 991-100
The length contains all the bytes transmitted after the length byte with the exception of the two
checksum bytes. The maximum block length allowed by the SECS-I is 254 bytes and the minimum is
10 bytes.
The reverse bit (R bit) indicates the direction of the message. The R bit (MSB) is set to "0" for
messages to the reading device and "1" for messages to the host.
The device ID is a unique number to establish the connection with the reading device. It consists of
an 8-bit gateway ID (bit 0-7) and a 7-bit reader ID (bit 8-14). The gateway ID in the delivery state
corresponds to the last two hexadecimal characters of the serial number of the reader. The reader ID
has the value 0x01 in the delivery state. Of course, the device ID can be changed via the
corresponding parameters Gateway ID (->Parameter 0) and Reader ID (->Parameter 0x0B) within the
validity range. See example with Reader ID 0x01 and Gateway ID 0x00:
Upper Devic-ID
(Reader-ID)
R-Bit 0 0 0 0 0 0 1
Lower Device-ID
(Gateway-ID)
0 0 0 0 0 0 0 0
Byte
MSB
Description
Length
0
Length without checksum
Header
1
R
Upper Device ID (reader ID)
2
Lower Device ID (gateway ID)
3
W
Upper Message ID (stream)
4
Lower Message ID (function)
5
E
Upper block number
6
Lower block number
7
System byte 1
8
System byte 2
9
System byte 3
10
System byte 4
Data
11-254
Message data
Checksum
255, 256
16-bit checksum