12. Communication Design Examples z When X0 = OFF, MM420 will stop. PLC D MM420 ， PLC sends: 02 06 00 047A 0000 7A MM420 D PLC ， PLC receives: 02 06 00 FB11 0000 EE Register for sent data (PLC sends out message): Register for received data (MM420 responds with messages): z There are 2 situations for RS communication: M1123 for normal communication and M1129 for receiving timeout. When communication time-out occurred, M2 can be used to retry Remarks: z Siemens MM420 series AC motor drive uses USS communication protocol and allows maximum of one master connected with 31 slaves. Slave ID: 0~31 The structure of the communication message:
DVP-PLC Application Examples 12-47 Register DATA Explanation D121 low 00H Station No. (range: 0~31, corresponding to hex 00H~1FH) D121 high FBH Status word (Refer to Remarks for definitions) D122 low 34H D122 high 33H Frequency (4000H = base frequency 50Hz, 3333H = 40Hz) D123 low 33H D123 high CBH Tail. (XOR result of all the bytes before this byte) Register DATA Explanation D100 low 02H Head. Fixed as 02H (start of the message) D100 high 06H The number of the following bytes D101 low 00H Station No. (range: 0~31, corresponding to hex 00H~1FH) D101 high 04H Control word (Refer to Remarks for definitions) D102 low 7AH D102 high 00H Frequency (0000H = 0 Hz.) D103 low 00H D103 high 7AH Tail.
(XOR result of all the bytes before this byte) Register DATA Explanation D120 low 02H Head. Fixed as 02H (start of the message) D120 high 06H The number of the following bytes D121 low 00H Station No. (range: 0~31, corresponding to hex 00H~1FH) D121 high FBH Status word (Refer to Remarks for definitions) D122 low 11H D122 high 00H Frequency (0000H = 0 Hz.) D123 low 00H D123 high EEH Tail. (XOR result of all the bytes before this byte)