Master-Slave mode

Application

A further possibility is the exchange of data between a master and up to 7 slaves. The address of the slave is set accordingly with the DIP switch. The address may only be used once for each channel. Here too the control byte 1 CB1 must be set to TRUE as bit 0 "Start BIT". Bits 3...5 are used to set the slave address of the target device. The terminal then sends telegrams to the corresponding slave. If the terminal receives a response, this is displayed in the status.

Example: Task – you want to speak to slave 2.

Set bit 0 to TRUE in order to start data exchange. Bit 3 must then be set in order to speak to slave 2. As soon as the reply from slave 2 is received (after approx. 20 ms), the master terminal confirms this in the status byte by setting bit 4. The address is always counted +1 in the status byte (see table).

CB1

Bit	CB1.7	CB1.6	CB1.5	CB1.4	CB1.3	CB1.2	CB1.1	CB1.0
Name	RegAccess	reserve	Add3	Add2	Add1	Scan	EnergyScan	Start
Value	0	0	0	0	1	0	0	1

SB1

Bit	SB1.7	SB1.6	SB1.5	SB1.4	SB1.3	SB1.2	SB1.1	SB1.0
Name	RegAccess	Error	Add3	Add2	Add1	Scan	EnergyScan	Start
Value	0	0	0	1	0	0	0	1

Address	Control byte bit 3...5		Status byte bit 3...5
Slave 1	0_dec	000_bin	1_dec	001_bin
Slave 2	1_dec	001_bin	2_dec	010_bin
Slave 3	2_dec	010_bin	3_dec	011_bin
Slave 4	3_dec	011_bin	4_dec	100_bin
Slave 5	4_dec	100_bin	5_dec	101_bin
Slave 6	5_dec	101_bin	6_dec	110_bin
Slave 7	6_dec	110_bin	7_dec	111_bin

Hence, you can now poll the terminals at any desired speed and in any desired rhythm. If you only send data very rarely to a slave, remember that the watchdog in the slave terminal can trigger. The watchdog time in the slave is approx. 400 ms and can be set in register R38. The default value is 20 and must be multiplied by 20 ms.

If a slave does not answer, then either the radio connection is disturbed or bit 0 of the control byte on the slave side is not set; the master terminal sets the error bit 6. The error code is contained in the high nibble in SB2.

If you want to address a new slave, make sure that the data bytes 0...9 are updated on the new slave at the same time. When the slave replies, you should only accept the data from the new slave if the new slave address appears in the status and the error bit is not set.