Bender A-ISOMETER AGH575S-6, Руководство по эксплуатации

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Serial interfaces
41 TGH1384en/06.2005
5.3 BMS protocol
This protocol is an essential part of the Bender Measuring Device Interface.
Data transmission generally makes use of ASCII characters.
Interface data are:
Baud rate: 9600 baud
transmission: 1 start bit, 7 data bits, 1 parity bit, 1 stop bit (1, 7, E, 1)
Parity: even
Checksum: sum of all transmitted bytes = 0 (without CR and LF)
The BMS bus protocol works according to the MASTER-SLAVE principle.
That means that one device represents the MASTER while all other bus nodes
are SLAVES. It is important that only one MASTER is present in each net-
work. All bus nodes are identified by a unique address. The MASTER scans
all other devices on the bus cyclically, listens to their signals and then carries
out specific commands. Bus address 1 must be assigned to the Master, thus
to one of the IRDH275B devices.
5.3.1 BMS Master
A Master can query all warning and operating messages from a slave.
If the bus address 1 has been selected for one IRDH275B, this device auto-
matically represents the Master, that means that all addresses between 1 and
150 are cyclically scanned via the BMS bus for alarm and operating messages.
If the Master receives no answer from five subsequent addresses, the scan-
ning cycle is started again. If the Master recognizes incorrect answers from a
slave, the fault message "Fault RS485" is issued by the Master.
Fa u l t R S 4 8 5
R s = 0 1 1 k
W . H