MD MODE OPTION (Factory Installed)
The GEN supply is capable of operating in a multi drop environment
serial communications on a single serial bus. A maximum of 31 GEN suppli
es can operate in this si
gle bus. Upon power up the Gen will enter the point
point mode in which it is assumed that only 1
supply will operate on a serial bus. MD Mode must be enabled
Ref. Section 7.10.2.2. The user must
set all Slave supplies to a u
nique address. No two supplies may have the same address.
Refer to section 7.10.2.2. MD Mode is entered into via a Single byte command. In MD Mode the Ma
ter supply shall operate in one of the two serial mo
des, RS232 or RS485, depending upon the rear
panel DIP switch setting and the Slave supplies shall operate in the RS485 s
In MD Mode the SRQ generated by the supply is replaced by a single byte SRQ sent two times in s
The SRQ byte, in binary, will contain the address of the supply in the least significant 5 bits
with bits 5 and 6 set to logic zero and bit 7 set to logic 1. Ref. Table 7
In MD Mode it is possible to have one supply issue
an SRQ while another supply is transmitting
data/response to a command. When this happens, the HOST PC will receive garbled data and a
sume that the data/response was corrupted and thus re
be lost. The method of re
covery will be SRQ retransmission, Ref. Section 7.4.5, or polling all a
supplies to see who issued the SRQ
available by reading the SEVE? Register.
MD Mode SRQ Retransmission
The supply can be commanded to retransmit the SRQ at regular inte
vals until it is answered to by the
HOST PC (Ref. Section 7.10.2.4). The retransmission interval is 10 ms plus the supply address mult
