2 Functions of Devices in DVP-PLC Master PLC will not read/write from/into the new Slave PLC to the LINK, unless it re-detects the ID of Slave PLCs. k) Master PLC conducts reading before writing. The ranges of Slave PLCs to be read/written will follow the setting. l) Master PLC will move to the reading/writing of the next Slave PLC after finishing reading/writing the current Slave PLC. 10. Auto mode and maual mode: a) Auto mode (M1351 = On): Master PLC automatically reads/writes from/to Slave PLC and stops when M1350/M1351 = Off to terminate PLC LINK. b) Manual mode (M1352 = On): When M1352 = On, you also have to set up the times of polling in D1431.
One time of polling refers to the completion of reading and writing all Slaves. After the PLC LINK is enabled, D1432 will start to count how many LINKs have been done. When D1431 = D1432, PLC LINK stops and M1352 is reset. To re-enable PLC LINK in the manual mode, simply turn “On” M1352 and D1431 will starts to count the times of LINK again. c) Note: i) Automatic mode (M1351) and manual mode (M1352) cannot be “On” at the same time; otherwise PLC LINK will stop and M1350 will be reset. ii) For EH2/SV/EH3/SV2: M1350 has to be reset before switching between automatic mode and manual mode. For SA/SX/SC: No such restriction.
iii) When M1355 = On, M1360 ~ M1375 (M1440 ~ M1455) will be the flags for the PLC designated to be connected to. Therefore, no matter how many PLCs are actually connected, the PLC LINK function will continue to send read/write instruction in cycle according to the designated flags. iv) The communication timeout is adjustable (D1129, range: 200 ≤ D1129 ≤ 3,000). If D1129 falls out the range, PLC will determine the time by 200 or 3,000. The timeout setting of PLC LINK is only valid if it is set before the LINK is enabled. If the number of read/written data >16, the communication timeout shall be > 500ms in case a communication timeout may occur.
v) PLC LINK is only workable when the baud rate is > 1,200bps. If the baud rate is timeout setting shall be > 1 second. vi) The communication is unworkable when the number of read/written data = 0. vii) PLC LINK does not support the reading/writing from/to 32-bit counters (C200 ~ C255). viii) The maximum set value for D1399 is 230. If the set value is bigger than 230, PLC will automatically correct it as 230. The minimum set value for D1300 is 1. If the set value is smaller than 1, PLC will automatically correct it as 1. ix) Setting up of D1399 has to be done before PLC LINK is enabled. After PLC LINK is enabled, setting up D1399 will not result in any changes.
x) Advantages (when using a multi-layer network): Assume you are using a network with 3 layers and the first and second layer and the second and third layer are using PLC LINK for communication, the IDs in the second and third layer will definitely overlap due to the old version of PLC LINK detects only Slave ID#1 ~ 16. When the IDs of Slave and Master overlap, PLC LINK will ignore the PLC of overlapping ID, resulting in the DVP-PLC Application Manual 2-133