DrStranglove
Member
I'm doing a project that adds some Honeywell DCS writes to an existing Modbus link that is currently working fine, but only doing reads. When the DCS attempts to write any more than about 10 flags to the PLC, it crashes the link.
I've had this problem with other PLCs and found that the issue is timing: The DCS wants an immediate read-back to confirm that the data got there, but the comm modules want to pass the data first to the PLC processor then back, or some such nonsense, causing a delay that is unacceptable to DCS. There's always some little trick like Pass-through or putting the command block in OB1, but I haven't figured it out yet for the TI545/2573-mod.
Anyone know this one?
Thanks!
I've had this problem with other PLCs and found that the issue is timing: The DCS wants an immediate read-back to confirm that the data got there, but the comm modules want to pass the data first to the PLC processor then back, or some such nonsense, causing a delay that is unacceptable to DCS. There's always some little trick like Pass-through or putting the command block in OB1, but I haven't figured it out yet for the TI545/2573-mod.
Anyone know this one?
Thanks!
