Panasonic kw9m User Manual

Also see for KW9M Eco-Power Meter: User manual User manual Installation instructions

Contents

KW9M Eco-POWER METER39Chapter 6 Communications6.1 Communication ProceduresCommunication starts with command transmission from the host computer (hereafter Master) and endswith the response of Eco-POWER METER (hereafter Slave).• Response with dataWhen master sends reading command, slave responds with thecorresponding set value or current status.• AcknowledgementWhen master sends setting command, slave responds by sendingthe acknowledgement.• Negative acknowledgementWhen master sends a non-existent command or value out of the settingrange, the slave returns negative acknowledgement.• No responseSlave will not respond to master in the following cases.• Global address “FF” (MEWTOCOL) is set.• Broadcast address “00H” (Modbus protocol) is set.• Communication error (framing error, parity error)• CRC-16 discrepancy (Modbus RTU mode)• CS discrepancy (DL/T645)6.2 Communication timing◆The minimum access time from the master is 1 sec. (Minimum time for update the data)Eco-POWER METER may not response due to noise and so on, be sure to check that it receives theresponse from Eco-POWER METER.◆In order to improve the communication quality, we recommend to send the transmission again.Communication timing of RS485◇Eco-POWER METER (Slave) sideWhen Eco-POWER METER (Slave) starts transmission to RS485 communication line, it is arrangedso as to provide an idle status transmission period of about 1 to 99ms (setting available) beforesending the response to ensure the synchronization on the receiving side. After sending the response,master can disconnect the transmitter from the communication line within transmission period 20ms.◇Master side (Cautions of setting a program)At communication, keep the following conditions.1) Set the program so that the master can disconnect the transmitter from the communication linewithin the transmission period of about 20ms after sending the command in preparation forreception of the response from Eco-POWER METER (Slave).2) To avoid collision of transmissions between the master and Eco-POWER METER (Slave), send anext command after checking that the master received the response.Master SlaveCommandDataAcknowledgementCommandNegativeacknowledgementCommandNo responseCommand